main: Slight refactor of main. Improve color situation.

Several issues are addressed here:
- main() is large, and half of it is only used if we're not rasterisk;
  fixed by spliting up the daemon part into a separate function.
- Call ast_term_init from rasterisk as well.
- Remove duplicate code reading/writing asterisk history file.
- Attempt to tackle background color issues and color changes that
  occur. Tested by starting asterisk -c until the colors stopped
  changing at odd locations.
- Remove unused term_prep() and term_prompt() functions.

ASTERISK-25585 #close

Change-Id: Ib641a0964c59ef9fe6f59efa8ccb481a9580c52f

include/asterisk/term.h

@@ -67,8 +67,8 @@ extern "C" {
 #define COLORIZE_FMT	"%s%s%s"
 #define COLORIZE(fg, bg, str)	ast_term_color(fg,bg),str,ast_term_reset()
 /*! \brief Maximum number of characters needed for a color escape sequence,
- *         plus a null char */
-#define AST_TERM_MAX_ESCAPE_CHARS   12
+ *         and another one for a trailing reset, plus a null char */
+#define AST_TERM_MAX_ESCAPE_CHARS   23
 #define AST_TERM_MAX_ROTATING_BUFFERS	15
 
 /*! \brief Colorize a specified string by adding terminal color codes
@@ -137,10 +137,6 @@ char *term_strip(char *outbuf, const char *inbuf, int maxout);
 
 void term_filter_escapes(char *line);
 
-char *term_prompt(char *outbuf, const char *inbuf, int maxout);
-
-const char *term_prep(void);
-
 const char *term_end(void);
 
 const char *term_quit(void);