Sped up ActorMap.ActorsInBox.

- By ensuring both the add and remove actor lists are sets, we ensure the partitioning bins will contain only distinct actors. We can remove the HashSet and Distinct in ActorsInBox and ActorsInWorld which provides a nice speedup for queries. ActorsInBox sees nearly a 3x speedup in the RA shellmap.
Add MaxSpread to Warhead to allow setting a specific area of effect.
Ion Cannon now scorches the whole hit area, and uses higher Spread + low
MaxSpread to increase damage within the hit area, but keep area of effect
itself relatively low.
Additionally increased damage to make it less inferior to Nukes.
Make sure actors are removed from control groups when captured

Fixes #5976.
don't use country specific decimal separators for decimals
same for double
Merge pull request #5853 from RoosterDragon/actormap-perf

Sped up ActorMap.ActorsInBox.
Merge pull request #6036 from Mailaender/trait-export-decimal-separators

Fixed country specific decimal separators in the traits documentation
Add Buildable.BuildAtProduction.

This allows actors to be restricted to specific production structures.
Merge the RA aircraft queues. Closes #5961.
Add BuildAtProductionType to boats/subs.
Increase MCV selection priority.
Make lobby chat field have keyboard focus by default.
Cnc: Increase MCV selection priority.
Merge pull request #6052 from deniz1a/mcv-pri

Increase MCV selection priority
Merge pull request #6035 from pchote/merge-air-queues

Merge RA aircraft queues
Merge pull request #5941 from reaperrr/spread-upgrade

Added MaxSpread for more control over maximum area of damage
Merge pull request #6053 from deniz1a/chat-focus

Closes #4722
ClonesProductionUnits:
	string[] CloneableTypes	checks Cloneable.Types

Cloneable:
	string[] Types checked by ClonesProductionUnits.CloneableTypes

Added INotifyOtherProduction
	for notifying self when another actor
	produces a unit.
Merge pull request #5910 from Phrohdoh/CloningVats

Added cloning trait pair for RA2-style Cloning Vats.