[8475] fixed some gcc-warnings

all warnings from Wunused
and some from Wall

cause unused may be most interesting for some:
they were in following files:
src/game/Level2.cpp
src/game/Map.cpp
src/game/SpellAuras.cpp
src/game/Unit.cpp
src/mangosd/Master.cpp
but i guess mostly someone just fogot to remove this code

for some unsigned vs signed warnings i used:
ack "for.*int .*size\(\)" | ack -v uint

also note for coding:
if you do something like
    if( a && b || c)
just place parentheses around (a && b) && always will have
precedence over || but without parentheses this could be overseen
quite fast (at least that's my guess why gcc will warn for this)

Signed-off-by: balrok <der-coole-carl@gmx.net>

src/game/TradeHandler.cpp

@@ -592,7 +592,7 @@ void WorldSession::HandleSetTradeItemOpcode(WorldPacket& recvPacket)
 
     // check cheating, can't fail with correct client operations
     Item* item = _player->GetItemByPos(bag,slot);
-    if(!item || tradeSlot!=TRADE_SLOT_NONTRADED && !item->CanBeTraded())
+    if (!item || (tradeSlot != TRADE_SLOT_NONTRADED && !item->CanBeTraded()))
     {
         SendTradeStatus(TRADE_STATUS_TRADE_CANCELED);
         return;