Fix for compile error on MSVC express 2005. 2 is ambiguous so we need to use 2.0

svn path=/branches/marble/0.4/marble/; revision=718441

src/lib/TileCreator.cpp

@@ -68,7 +68,7 @@ void TileCreator::run()
     } 
 
     // Calculating Maximum Tile Level
-    float approxMaxTileLevel = log( imageWidth / ( 2 * tileSize ) ) / log( 2 );
+    float approxMaxTileLevel = log( imageWidth / ( 2.0 * tileSize ) ) / log( 2.0 );
 
     int  maxTileLevel = 0;
     if ( approxMaxTileLevel == int( approxMaxTileLevel ) )