bring in the code that was discussed on Mantis #6068,

which is the basis for several simplifications and fixes
to the CLI interfaces.

The core is in cli.c, some documentation on a new function
to help command completion is in cli.h, and one line of
glue code in the other two files.

Next step is to bring in the patches described in #6066 and
other simplifications.



git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@15817 65c4cc65-6c06-0410-ace0-fbb531ad65f3

asterisk.c

@@ -2031,6 +2031,7 @@ int main(int argc, char *argv[])
 	ast_ulaw_init();
 	ast_alaw_init();
 	callerid_init();
+	ast_builtins_init();
 	ast_utils_init();
 	tdd_init();
 	/* When Asterisk restarts after it has dropped the root privileges,