LUA and trait documentation fixes

- Typo in documentation ("proximitry").
- Add spaces between sentences.
- Remove most occurrences of "  " (two spaces) unless clearly used as indendation
- Punctuation (although no fullstop after filenames like "notifications.yaml").

OpenRA.Mods.Common/Scripting/Properties/MissionObjectiveProperties.cs

@@ -108,7 +108,7 @@ namespace OpenRA.Mods.Common.Scripting
 		}
 
 		[ScriptActorPropertyActivity]
-		[Desc("Returns true if this player has lost all units/actors that have" +
+		[Desc("Returns true if this player has lost all units/actors that have " +
 			"the MustBeDestroyed trait (according to the short game option).")]
 		public bool HasNoRequiredUnits()
 		{