Added implementation for the new command INIT_CMD_SIGNAL.

The implementation looks up the named service by using
`svc_parse_jobstr`. The callbacks for `svc_parse_jobstr` has been
augmented to accept a user data parameter. For this use case,
a carrier for the actual signal was needed. The address of the
signal parameter is taken and passed on as a `void *`. The
callback then simply deferences it as an int - the signal number.

.gitignore

@@ -47,4 +47,4 @@ GTAGS
 /.built
 
 # VS Code user settings
-.vscode
+.vscode