WIP: Added the initial process table implementation.

Wrote a basic process table implementation with CC's vectors and hash
maps. So far, it looks like it does not really work.

src/ui-socket.h

@@ -21,8 +21,9 @@ struct process_info {
   uid_t UID;
 };
 
-// For default socket location, set socket_path = NULL.
-int init_ui_socket(const char *socket_path);
+int init_ui_socket();
+
+void destroy_ui_socket();
 
 int interactive_access(const char *filename, struct process_info pi);