Convert damage modifiers to integer percentages.
Convert speed modifiers to integer percentages.
Convert firepower modifiers to integer percentages.
Rename ProneSpeed to SpeedModifier in TakeCover.
Upgrade mod rules.
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.
Merge pull request #6218 from pchote/percentmods

Change attribute modifiers to use integers.
Merge pull request #6183 from UberWaffe/6030Fix_UpgradeRules

Closes #6177
Closes #6222
Closes #6240
Closes #6245