res_geolocation: Address user issues, remove complexity, plug leaks

* Added processing for the 'confidence' element.
* Added documentation to some APIs.
* removed a lot of complex code related to the very-off-nominal
  case of needing to process multiple location info sources.
* Create a new 'ast_geoloc_eprofile_to_pidf' API that just takes
  one eprofile instead of a datastore of multiples.
* Plugged a huge leak in XML processing that arose from
  insufficient documentation by the libxml/libxslt authors.
* Refactored stylesheets to be more efficient.
* Renamed 'profile_action' to 'profile_precedence' to better
  reflect it's purpose.
* Added the config option for 'allow_routing_use' which
  sets the value of the 'Geolocation-Routing' header.
* Removed the GeolocProfileCreate and GeolocProfileDelete
  dialplan apps.
* Changed the GEOLOC_PROFILE dialplan function as follows:
  * Removed the 'profile' argument.
  * Automatically create a profile if it doesn't exist.
  * Delete a profile if 'inheritable' is set to no.
* Fixed various bugs and leaks
* Updated Asterisk WiKi documentation.

ASTERISK-30167

Change-Id: If38c23f26228e96165be161c2f5e849cb8e16fa0

res/res_geolocation/geoloc_gml.c

@@ -247,6 +247,11 @@ struct ast_xml_node *geoloc_gml_list_to_xml(const struct ast_variable *resolved_
 
 	SCOPE_ENTER(3, "%s", ref_string);
 
+	if (!resolved_location) {
+		SCOPE_EXIT_LOG_RTN_VALUE(NULL, LOG_ERROR, "%s: resolved_location was NULL\n",
+			ref_string);
+	}
+
 	shape = ast_variable_find_in_list(resolved_location, "shape");
 	if (ast_strlen_zero(shape)) {
 		SCOPE_EXIT_LOG_RTN_VALUE(NULL, LOG_ERROR, "%s: There's no 'shape' parameter\n",