Switch server to use new style ManaChange_Struct (#1843)

This will allow us to fix some bugs the current handling has.

Note: the decoder isn't needed since the client always sends it up as a
0 length packet.

common/patches/uf.cpp

@@ -1390,20 +1390,6 @@ namespace UF
 		FINISH_ENCODE();
 	}
 
-	ENCODE(OP_ManaChange)
-	{
-		ENCODE_LENGTH_EXACT(ManaChange_Struct);
-		SETUP_DIRECT_ENCODE(ManaChange_Struct, structs::ManaChange_Struct);
-
-		OUT(new_mana);
-		OUT(stamina);
-		OUT(spell_id);
-		OUT(keepcasting);
-		eq->slot = -1; // this is spell gem slot. It's -1 in normal operation
-
-		FINISH_ENCODE();
-	}
-
 	ENCODE(OP_MercenaryDataResponse)
 	{
 		//consume the packet