Make FMVPlayer in TD use a completely black background

Fixes #6211.
Make FMVPlayer in RA use a completely black background
5936 Advanced Power Plant have a different layout in the original
Merge pull request #6230 from havok13888/AdvancedPowePlant

#5936 Advanced Power Plant have a different layout in the original
Merge pull request #6220 from obrakmann/fix6211

Make background of FMVPlayers in TD and RA black
avoid NullReferenceException in updatedRegion

fixes #6166
Merge pull request #6226 from Mailaender/shroud-updatedregion-nre

Fixed a crash when there are no actors to reveal shroud on the map.
Fixed UpgradeRules for #6030.
Fixed Warhead ValidTargets and InvalidTargets.
#6030 regression fix. Added EffectivenessAgainst <= 0 check to IsvalidAgainst for Warhead.
Made Effect, Resource and Smudge warheads return 0% effective against actors.
Fixed custom weapon rules in maps.
Adds Diplomacy keywords for ValidTarget checks.

Changes:

Allows diplomacy stance checks to be done on warheads and weapons, using keywords in ValidTargets and InvalidTargets.
Additional changes: Changed Weapon.Impact to use Target instead of WPos.
Split out some common functionality to DamageWarhead from its derivatives.
Ioncannon changed to AbsoluteSpreadDamage.
Detonating Madtank now affects other Madtanks, but still not itself.
Changed LaserZap projectiles to AbsoluteSpreadDamage.