Fixed member initialization order GCC complains about.
Removed some unused code.
Simplify the use of TilesetManager::mWatcher.

Only add a tileset image file to mWatcher after a tileset image is loaded
by a thread, and never stop watching that file because it persists in the
tileset image cache.
Delete TilesetManager::mTilesetImageCache in ~TilesetManager().
Copied a BuildingMap change from TileZed.
Updated the WorldEd icon.

It used to look like a castle, now it looks like a W.
Changed dist.tcl to not copy vcredist_x86.exe.

WorldEd is now a subdirectory of TileZed and TileZed includes that file.