migrate maps, new map, minor fixes

This probably fixes bug #839 - mine time was hardcoded to 3000 in Attack, instead of using the "0 as undefined" input that other places were using. When re653e96b0ec3 started paying attention to the input parameter, this previously ignored value became a problem.

- Take girder height into account (fix issue #908) - Fix off-by-2 error in girder placement - Some tweaks to allow for more girders placed

Added param for rounds in techracer. Also some support for hand-drawn map placed stuff.

reduce volume a bit more. also fix engine hint

50% volume on music to make sheepluva happy

add simple build instructions

Long awaited hwmap<->txt converter, which took less than hour to make

Move SDLNet_TCP_Send to its own thread

fml