Wifi game integration (combat mechanics)

Fully working (multiplayer) wifi game mechanics back-end.

@mheni let me know if you have feedback on the code.

Can confirm proper functioning on NDS (tested with minimum working example:)

For a MWE see 4dbbc492 on test/custom_wifi_screen_shit. For it to run in the emulator you need to comment out the code related to connecting to wifi. suggested solution is to locally reverse commit f0ea3b44 "less printing" (and then fix possible compile errors which may occur)

(closes #6. If you disagree lmk)