Refactor: introduce telinit and a new initctl tool w/ API

- Reduce size of `helpers.c`, for linking against new `initctl` tool,
  by moving out functions to `pid.c` and `exec.c`
- Add `AF_UNIX` API to Finit, to complement old `/dev/initctl` FIFO
- Let old FIFO API be used by init/telinit: `init <q | 1-9>`
- Move all advanced initctl code from `client.c` to `initctl.c`, yes
  its a bit confusing to call the *new* tool the same as the old FIFO
  but this is more in line with what, e.g Upstart does.
- Move all advanced server side code from `plugins/initctl.c` to `api.c`
- Update TODO with upcoming inetd syntax change and dynamic events.
- Temporarily fix display of inetd services from `initctl status -v`

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

finit.c

@@ -53,11 +53,29 @@ char *console   = NULL;
 
 uev_ctx_t *ctx  = NULL;		/* Main loop context */
 
+static int banner(void)
+{
+	if (!verbose)
+		return 0;
+
+	delline();
+#ifdef INIT_HEADING
+	echo("%s", INIT_HEADING);
+#else
+	echo("Finit v" VERSION);
+	echo("===================================================================");
+#endif
+	return 0;
+}
 
 int main(int argc, char* argv[])
 {
 	uev_ctx_t loop;
 
+	/*
+	 * finit/init/telinit client tool uses /dev/initctl pipe
+	 * for compatibility but initctl client tool uses socket
+	 */
 	if (getpid() != 1)
 		return client(argc, argv);
 
@@ -190,6 +208,9 @@ int main(int argc, char* argv[])
 	if (quiet)
 		verbose = 0;
 
+	/* Start new initctl API responder */
+	api_init(&loop);
+
 	/*
 	 * Enter main loop to monior /dev/initctl and services
 	 */