Don't nest asyncio input hooks....
Don't nest asyncio input hooks.
This fixes the "event loop already running" error.
For prompt_toolkit 2.0: this will still nest the event loops, but that's fine,
because we have the asyncio event loop running an prompt_toolkit's custom loop.
They don't interfere with each other.
For prompt_toolkit 3.0: we only use one asyncio event loop when "%gui asyncio"
is used. The terminal prompt will now use the active asyncio event loop.
