Fix energy and heat on combustion engines reseting after 65535 and 6553.5 respectively. It was caused because the messages were sending only one byte at a time while max heat (100000) needs 3 bytes to be sent (a short is 2 bytes so each message can send 2 bytes instead of one).
Merge pull request #579 from psxlover/EngineGui

Fix #577 energy and heat on combustion engines reseting.