* Add preliminary support for TTY Serial/UART (#15)
* Use shadow_buffer instead of VGA buffer to get a framebuffer-agnostic TTY supprot
* Added menu browsing & inputs from Serial TTY (#15)
* Add fix for degree symbol on TTY. Correct serial.c & serial.h file created with CRLF (#15)
* Move tty_error_redraw() to insure correct redraw when a error occurs
* Many reindent / cleanup
* Various optimization from @martinwhitaker comments
This is needed for subsequent changes. If we do ever get presented with
a frame buffer larger than 8192x8192 pixels, we'll need to think again
about how to manage it.