Skeleton for the process tables implementation

Wrote a skeleton for the future process table implemntation. Aslo
slightly edited the ui-socket interface.

src/ui-socket.h

@@ -24,6 +24,6 @@ struct process_info {
 // For default socket location, set socket_path = NULL.
 int init_ui_socket(const char *socket_path);
 
-int ask_access(const char *filename, struct process_info pi);
+int interactive_access(const char *filename, struct process_info pi);
 
 #endif // !UI_SOCKET_H