gasyncio - A minimalistic asyncio event loop based on the GLib main event loop

So far only a proof-of-concept.

Defines GAsyncIOEventLoopPolicy and GAsyncIOEventLoop.

Use loop.run_application(app, argv) to run Gio.Application. While the application is running, the asyncio event loop will function normally, run by the GLib main event loop.

Use loop.run_without_glib_until_complete(future) for cleanup.

The following should be semantically equivalent:

policy = asyncio.set_event_loop_policy(gasyncio.GAsyncIOEventLoopPolicy())
loop = asyncio.get_event_loop()
loop.start_slave_loop()
App().run(sys.argv)
loop.stop_slave_loop()
loop.close()
asyncio.set_event_loop_policy(policy)
del loop, policy

loop = gasyncio.GAsyncIOEventLoop()
loop.start_slave_loop()
App().run(sys.argv)
loop.stop_slave_loop()
loop.close()
del loop

gasyncio.GAsyncIOEventLoop().run(App(), sys.argv)