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/PlayerProperties.cs

@@ -60,7 +60,7 @@ namespace OpenRA.Mods.Common.Scripting
 				.ToArray();
 		}
 
-		[Desc("Returns all living actors of the specified type of this player")]
+		[Desc("Returns all living actors of the specified type of this player.")]
 		public Actor[] GetActorsByType(string type)
 		{
 			var result = new List<Actor>();