Enumify registers in AT Mega VAPI
Have configure do a better job of picking libvala
Make pkg-config do something sensible

Rather than using the system pkg-config paths, directly manipulate the
pkg-config path so that it will only look for the appropriate libraries,
and then create some base pkg-config files for a GLib compatibility
layer (mostly just typedefs).
Create a system to do asynchronous calls on an AVR

This is a modified form of Vala's async mechanism that uses a different
underlying main loop from the GLib one. This one should be AVR friendly.
Include indentation config for C files