Add include headers
Refactor main cons functions

It's a lot easier to have three function calls: buffer, write, and
flush. cons_buffer() is to be used in conjunction with
cons_flush() during VBLANK, while cons_write() ensures writing
during VBLANK (no need to buffer then wait until VBLANK to flush).
Add ARP support
Add arp-comm example
Add main header

This can be used to simply include all the usable headers in a
project.