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
Shouldn't the `tty` parameter to the `UARTDev` constructors be the literal strings `'tty0'` and `'tty1'` instead of `termId` and `termIdTwo`?
The uart sends the command to the worker which only understands `'tty0'` and `'tty1'` - it doesn't know about the HTML element ids. It just happens that the element ids are the strings `'tty0'` and `'tty1'` so everything works.