Fixes for TD Husks and unit labels

Fixes fixes fixes!

done :|

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Add constants for the 8 main facing values to Lua. Fixes #4490
Add Actor.OnDamaged

Allows the AI to react to its units being attacked.
Add Actor.Guard
Merge pull request #4678 from dan9550/td_medtank

Fixes for TD Husks and unit labels
Merge pull request #4662 from obrakmann/lua

Add Actor.Guard, Actor.OnDamaged and constants for facing values to Lua interface
Pillbox unload fix
removed CurrentAdjacentCells from ctor
Merge pull request #4683 from Temeez/pillbox-fix

closes #4681
Adds selecting of all units matching the current type across the screen or map using Ctrl + T.
Merge pull request #4556 from pizzaoverhead/SelectUnitsByType

Select units by type
Add map beacons and radar pings
Add radar pings to BaseAttackNotifier and HarvesterAttackNotifier
Change spacebar key to move to the last visible radar ping location
Enable Obelisk charge anim and sound

Enables Obeliks charge anim and sound by using AttackTesla instead of AttackTurreted.
Match Obelisk charge anim speed with original

Without a high tick value the charge anim plays way too fast.
Merge pull request #4699 from reaperrr/patch-1

Fixes Obelisk Charge anim and sound
Fix OpenRA.Utility not being able to locate mod assemblies on Windows. Fixes #4498
Merge pull request #4702 from ScottNZ/utility

Fix OpenRA.Utility not being able to locate mod assemblies
Flood fill now treats similar grass/snow/desert tiles as the same - fixes #4695