TileShapeEditor: Fixed swapped x/y transform spinboxes.
TileShapeEditor: account for line with when drawing TileShapeItem.
EnflatulatorDialog.: Added tile grid item.
TextureMgr loads texture images asynchronously.
TextureMgr reloads texture images when they change on disk.
Added "Use virtual tilesets" option.

Defaults to off.  Changing it takes effect after restarting.
Changed a tooltip in VirtualTilesetDialog.
Misc FTW.
Remove VirtualTilesets.txt.

virtualtilesets.vts is used instead.
Some GCC fixes.
Removed missing virtualtilesetundoredo.cpp/.h
Call QPen::setCosmetic(true) for TileShapeEditor and Qt 5.
Hide the 'Enflatulator' menu command.