Another Main Loop

Event loop handler developed for wayvnc (Wayland VNC server) and wlvncc (Wayland VNC client) - see https://github.com/any1 Goals: * Portability * Utility * Simplicity Non-goals: * MS Windows (TM) support * Solving the C10K problem Features: * File descriptor event handlers * Timers * Tickers * Signal handlers * Idle dispatch callbacks * Thread pool * Interoperability with other event loops