Enhance AGI with several fixes:

 - Makes the structures handling external AGI commands a bit more thread-safe
 - Makes AGI transparently work with both live and hungup channels
 - DeadAGI is hence no longer necessary and is deprecated
 - CLI bug fixes
 - Commands will refuse to run if the channel is dead and the command is nonsensical
   for dead channels.


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@76707 65c4cc65-6c06-0410-ace0-fbb531ad65f3

include/asterisk/agi.h

@@ -43,11 +43,14 @@ typedef struct agi_command {
 	char *summary;
 	/* Detailed usage information */
 	char *usage;
-	struct agi_command *next;
+	/* Does this application run dead */
+	int dead;
+	/* Linked list pointer */
+	AST_LIST_ENTRY(agi_command) list;
 } agi_command;
 
 int ast_agi_register(agi_command *cmd);
-void ast_agi_unregister(agi_command *cmd);
+int ast_agi_unregister(agi_command *cmd);
 
 #if defined(__cplusplus) || defined(c_plusplus)
 }