Instead of passing function pointers, we're passing structs with context
now. The idea is the same, I/O functions require some struct with a
function pointer and some generic memory that only the output device
cares about. I/O just calls it.
VGA has been reworked to accomodate this change, as well as default
outputs being created for low-overhead use (such as interrupt handlers).
instead of stuffing all of the i/o stuff into the "kio" library, i've
decided to rework i/o to be a generic handler that takes in a function
pointer for putc, and does the rest of the logic onto that pointer.
That way, you can pass any function that can take in characters and move
them to buffers.
I'll do a writeup on this at some point to document it.
