This removes the startup cost of parsing hundreds of default actions
when action_alias or kitten_alias are used. Although the cost is on the
order of 1ms, this design feels cleaner and gives nicer debug config
output.
Now the time for importing the kitty.config module has been halved, from
16ms from 32ms on my machine. Also, the new architecture will eventually
allow for auto generating a bunch of python-to-C boilerplate code.
