Dual terminal support

Support for two terminals in the emulator. Closes #19 

Note that sometimes junk and/or the error message `mkdir: can't create directory '/tmp/root-runtime-dir': File exists` will appear in either terminal window; as far as I can tell this is related to how the login process is now handled in `/etc/inittab` and does not affect functionality in any way.

To switch between terminals, press the newly added arrow button in the top right corner of the terminal. Fullscreen state is maintained between switches. `gcc` compilation still happens in the first terminal window, but this can be changed later if necessary.

`hdgcc-mod.bz2` (the disk image) has been modified to start `getty` on boot. `/etc/inittab` and `/bin/autologin` were modified to achieve this.

There is a test setup running on http://tf2.intense.io:9000/#playground
That was deliberate on my part, I prefer not to use hardcoded constants and it makes sense if you think of a terminal canvas 'attaching' to a UART for I/O.