Added common eMessageType aliases.

src/Defines.h

@@ -540,6 +540,12 @@ enum eMessageType
 	mtPrivateMessage,  // Player to player messaging identifier
 	mtJoin,            // A player has joined the server
 	mtLeave,           // A player has left the server
+	
+	// Common aliases:
+	mtFail  = mtFailure,
+	mtError = mtFailure,
+	mtInfo  = mtInformation,
+	mtPM    = mtPrivateMessage,
 };