show a user friendly description of the starting unit template

closes #6209
Add support for C&C Generals .big archive files
beautify starting unit notification when joining server

move LobbySettingsNotification into it's own ServerTrait
Merge pull request #6255 from ScottNZ/generals

Add support for C&C Generals .big archive files
Suppress map change order when selecting the same map.  Fixes #6206.
Merge pull request #6271 from pchote/map-kick-fix

Avoid sending the map change order when selecting the same map.
Merge pull request #6217 from Mailaender/starting-units-classname

Fixed lobby start unit notifications not showing class names
Move common DoImpact(Target) method into DamageWarhead.
Remove more unnecessary plumbing.
Move warheads into mod code.
Convert weapon plumbing to use integer damage modifiers.
Further warhead streamlining.
Change EffectivenessAgainst to CanTargetActor.
Remove fp calculations from SpreadDamageWarhead.
Remove now-redundant AbsoluteSpreadDamageWarhead.
Convert versus to integers.
Increase falloff accuracy for large damage amounts.
Fix inner range filtering in HealthPercentageDamageWarhead.
Adds Diplomacy keywords for ValidTarget checks.

Changes:

Allows diplomacy stance checks to be done on warheads and weapons, using keywords in ValidTargets and InvalidTargets.
Ioncannon changed to limited Spread. (1000, 250, 100 damage in 1c1, 2c1, 2c8)