Revert "Add FlxGroup::revive()"

The following commit has been undone:
FlixelCommunity#110

And a tiny bit of documentation has been added describing the changes.

Discussion:
 - FlixelCommunity#185
 -
FlixelCommunity#30 (comment)

src/org/flixel/FlxGroup.as

@@ -573,21 +573,12 @@ package org.flixel
 		}
 
 		/**
-		 * Calls revive on the group itself and then on the group's members.
+		 * Calls revive on the group object. <i>Note: Does not revive any of the members!</i>
 		 */
 		override public function revive():void
 		{
 			// Revive the group itself
 			super.revive();
-
-			var basic:FlxBasic;
-			var i:uint = 0;
-			while(i < length)
-			{
-				basic = members[i++] as FlxBasic;
-				if((basic != null) && !basic.alive)
-					basic.revive();
-			}
 		}
 
 		/**