#185 Mek StructureTab.convertEngineType(int) doesn't account for non-Industrial ICE
I've noticed that whenever I try to select an internal combustion engine for a non-Industrial 'Mech, the engine and heat sink weight are adjusted accordingly, but the selected engine type immediately flips back to "Standard" and if I make other relevant changes (like to Walking MP, say) the engine is indeed immediately treated like a standard fusion one again.
I believe I've traced this back to megameklab.com.ui.Mek.tabs.StructureTab.convertEngineType(int). The only times that method even checks whether the value it's handed might be equal to Engine.COMBUSTION_ENGINE is when dealing with an industrial or primitive 'Mech; otherwise the case falls through and it returns 0 by default, which I can make an educated guess just so indeed corresponds to standard fusion. I'm not quite sure which hardcoded magic numbers the method should properly return from each separate switch statement, though, so I'd rather not risk messing with it myself either.
