Fix a loop closure bug in the weapons code.

Fixes #6597. Fixes #6599.
Minor style fixes.
fix broken objectives fine-tuning
Merge pull request #6612 from pchote/fix-warheads

Fix a loop closure bug in the weapons code.
build with latest Mono from @Xamarin
Merge pull request #6605 from Mailaender/travis-mono-latest

Build releases with latest Mono
Implement cell triggers. Closes #4400.
Update gdi04c to use cell triggers
Whitespace fixes
Merge pull request #6614 from abcdefg30/fixobj-fine-tuning

Fix broken objectives fine-tuning
Merge pull request #6574 from pchote/celltrigger

Implement cell triggers.
Add lua function OnInfiltrate
Added two diplomacy functions to lua
Ported monster tank madness to lua