Back from the dead - 2600box patch

[BenBrown]

An Atari 2600 emulator for Rockbox originally uploaded to http://www.rockbox.org/tracker/6048 by Anton Romanov on 22 September 2006.  Closed for being old and suffering from bit rot.  Well, I'm bringing this old Atari2600 patch back from the dead.

See Gerrit for the code, http://gerrit.rockbox.org/662

A lot of the work is done. Need to squash some bugs, but for the most part it's complete.  It "supposed" to work on any color target, but there are a few, keymaps to add/bugs to squash, before that happens.  No ugly hacks, however there is still extra code that needs to be pruned, and the formatting is not rockbox conformant.

I'm keeping an updated list of targets that compiles/runs against the plugin here http://foolsh.no-ip.org/projects/atari2600/wiki/Targets

Feel free to test and leave compliants feedback!