fix signed-compare warnings

The m_iSelection array could probably be made unsigned... IF we were
confident we never try to assign it a negative number, of which fact I'm
not convinced.

src/GameManager.cpp

@@ -2946,7 +2946,7 @@ void GameManager::GetStepsTypesForGame( const Game *pGame, vector<StepsType>& aS
 		// Some Styles use the same StepsType (e.g. single and versus) so check
 		// that we aren't doubling up.
 		bool found = false;
-		for( int j=0; j < aStepsTypeAddTo.size(); j++ )
+		for( unsigned j=0; j < aStepsTypeAddTo.size(); j++ )
 			if( (int) st == (int) aStepsTypeAddTo[j] ) { found = true; break; }
 		if(found) continue;