FPGAs overheat way too fast

[SmallJoker]

Affects master, after #383

The following setup, with 9 identically programmed FPGAs results constantly in 4 overheated FPGAs. instr = "A&D0/ ~A1/1&C2/0|2C////1&C4/A&B5/4|5B/////" Shift register program

~What I suspect: mesecon.do_overheat(pos) has an issue across mapblock borders. If I replace the 5th FPGA (functional) with a wire, the leftover FPGAs work again (after reprogramming).~ No relation there.

[Kimapr]

Maybe just remove FPGA overheat? They don't have any advantages to LuaCs otherwise. Same goes for microcontrollers.