Add CLI configuration documentation

This patch allows a module to define its configuration in XML in source, such
that it can be parsed by the XML documentation engine. Documentation is
generated in a two-pass approach:

1. The documentation is first generated from the XML pulled from the source
2. The documentation is then enhanced by the registration of configuration
   options that use the configuration framework

This patch include configuration documentation for the following modules:
 * chan_motif
 * res_xmpp
 * app_confbridge
 * app_skel
 * udptl

Two new CLI commands have been added:
 * config show help - show configuration help by module, category, and item
 * xmldoc dump - dump the in-memory representation of the XML documentation to
   a new XML file.

Review: https://reviewboard.asterisk.org/r/2278
Review: https://reviewboard.asterisk.org/r/2058

patches:
  on review 2058 uploaded by twilson



git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@381527 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channels/chan_motif.c

@@ -77,6 +77,145 @@ ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
 #include "asterisk/abstract_jb.h"
 #include "asterisk/xmpp.h"
 
+/*** DOCUMENTATION
+	<configInfo name="chan_motif" language="en_US">
+		<synopsis>Jingle Channel Driver</synopsis>
+		<description>
+			<para><emphasis>Transports</emphasis></para>
+			<para>There are three different transports and protocol derivatives
+			supported by <literal>chan_motif</literal>. They are in order of
+			preference: Jingle using ICE-UDP, Google Jingle, and Google-V1.</para>
+			<para>Jingle as defined in XEP-0166 supports the widest range of
+			features. It is referred to as <literal>ice-udp</literal>. This is
+			the specification that Jingle clients implement.</para>
+			<para>Google Jingle follows the Jingle specification for signaling
+			but uses a custom transport for media. It is supported by the
+			Google Talk Plug-in in Gmail and by some other Jingle clients. It
+			is referred to as <literal>google</literal> in this file.</para>
+			<para>Google-V1 is the original Google Talk signaling protocol
+			which uses an initial preliminary version of Jingle. It also uses
+			the same custom transport as Google Jingle for media. It is
+			supported by Google Voice, some other Jingle clients, and the
+			Windows Google Talk client. It is referred to as <literal>google-v1</literal>
+			in this file.</para>
+			<para>Incoming sessions will automatically switch to the correct
+			transport once it has been determined.</para>
+			<para>Outgoing sessions are capable of determining if the target
+			is capable of Jingle or a Google transport if the target is in the
+			roster. Unfortunately it is not possible to differentiate between
+			a Google Jingle or Google-V1 capable resource until a session
+			initiate attempt occurs. If a resource is determined to use a
+			Google transport it will initially use Google Jingle but will fall
+			back to Google-V1 if required.</para>
+			<para>If an outgoing session attempt fails due to failure to
+			support the given transport <literal>chan_motif</literal> will
+			fall back in preference order listed previously until all
+			transports have been exhausted.</para>
+			<para><emphasis>Dialing and Resource Selection Strategy</emphasis></para>
+			<para>Placing a call through an endpoint can be accomplished using the
+			following dial string:</para>
+			<para><literal>Motif/[endpoint name]/[target]</literal></para>
+			<para>When placing an outgoing call through an endpoint the requested
+			target is searched for in the roster list. If present the first Jingle
+			or Google Jingle capable resource is specifically targeted. Since the
+			capabilities of the resource are known the outgoing session initiation
+			will disregard the configured transport and use the determined one.</para>
+			<para>If the target is not found in the roster the target will be used
+			as-is and a session will be initiated using the transport specified
+			in this configuration file. If no transport has been specified the
+			endpoint defaults to <literal>ice-udp</literal>.</para>
+			<para><emphasis>Video Support</emphasis></para>
+			<para>Support for video does not need to be explicitly enabled.
+			Configuring any video codec on your endpoint will automatically enable
+			it.</para>
+			<para><emphasis>DTMF</emphasis></para>
+			<para>The only supported method for DTMF is RFC2833. This is always
+			enabled on audio streams and negotiated if possible.</para>
+			<para><emphasis>Incoming Calls</emphasis></para>
+			<para>Incoming calls will first look for the extension matching the
+			name of the endpoint in the configured context. If no such extension
+			exists the call will automatically fall back to the <literal>s</literal> extension.</para>
+			<para><emphasis>CallerID</emphasis></para>
+			<para>The incoming caller id number is populated with the username of
+			the caller and the name is populated with the full identity of the
+			caller. If you would like to perform authentication or filtering
+			of incoming calls it is recommended that you use these fields to do so.</para>
+			<para>Outgoing caller id can <emphasis>not</emphasis> be set.</para>
+			<warning>
+				<para>Multiple endpoints using the
+				same connection is <emphasis>NOT</emphasis> supported. Doing so
+				may result in broken calls.</para>
+			</warning>
+		</description>
+		<configFile name="motif.conf">
+			<configObject name="endpoint">
+				<synopsis>The configuration for an endpoint.</synopsis>
+				<configOption name="context">
+					<synopsis>Default dialplan context that incoming sessions will be routed to</synopsis>
+				</configOption>
+				<configOption name="callgroup">
+					<synopsis>A callgroup to assign to this endpoint.</synopsis>
+				</configOption>
+				<configOption name="pickupgroup">
+					<synopsis>A pickup group to assign to this endpoint.</synopsis>
+				</configOption>
+				<configOption name="language">
+					<synopsis>The default language for this endpoint.</synopsis>
+				</configOption>
+				<configOption name="musicclass">
+					<synopsis>Default music on hold class for this endpoint.</synopsis>
+				</configOption>
+				<configOption name="parkinglot">
+					<synopsis>Default parking lot for this endpoint.</synopsis>
+				</configOption>
+				<configOption name="accountcode">
+					<synopsis>Accout code for CDR purposes</synopsis>
+				</configOption>
+				<configOption name="allow">
+					<synopsis>Codecs to allow</synopsis>
+				</configOption>
+				<configOption name="disallow">
+					<synopsis>Codecs to disallow</synopsis>
+				</configOption>
+				<configOption name="connection">
+					<synopsis>Connection to accept traffic on and on which to send traffic out</synopsis>
+				</configOption>
+				<configOption name="transport">
+					<synopsis>The transport to use for the endpoint.</synopsis>
+					<description>
+						<para>The default outbound transport for this endpoint. Inbound
+						messages are inferred. Allowed transports are <literal>ice-udp</literal>,
+						<literal>google</literal>, or <literal>google-v1</literal>. Note
+						that <literal>chan_motif</literal> will fall back to transport
+						preference order if the transport value chosen here fails.</para>
+						<enumlist>
+							<enum name="ice-udp">
+								<para>The Jingle protocol, as defined in XEP 0166.</para>
+							</enum>
+							<enum name="google">
+								<para>The Google Jingle protocol, which follows the Jingle
+								specification for signaling but uses a custom transport for
+								media.</para>
+							</enum>
+							<enum name="google-v1">
+								<para>Google-V1 is the original Google Talk signaling
+								protocol which uses an initial preliminary version of Jingle.
+								It also uses the same custom transport as <literal>google</literal> for media.</para>
+							</enum>
+						</enumlist>
+					</description>
+				</configOption>
+				<configOption name="maxicecandidates">
+					<synopsis>Maximum number of ICE candidates to offer</synopsis>
+				</configOption>
+				<configOption name="maxpayloads">
+					<synopsis>Maximum number of pyaloads to offer</synopsis>
+				</configOption>
+			</configObject>
+		</configFile>
+	</configInfo>
+***/
+
 /*! \brief Default maximum number of ICE candidates we will offer */
 #define DEFAULT_MAX_ICE_CANDIDATES "10"
 
@@ -406,6 +545,7 @@ static int jingle_endpoint_cmp(void *obj, void *arg, int flags)
 
 static struct aco_type endpoint_option = {
 	.type = ACO_ITEM,
+	.name = "endpoint",
 	.category_match = ACO_BLACKLIST,
 	.category = "^general$",
 	.item_alloc = jingle_endpoint_alloc,