MapEdit: Actually save and restore last used tile set.
MapEdit: Always use XPM icon, and set window name and group.
Implement screen fade in/out.
MapEdit: Show current layer name in status bar.
Various stuff.

- Add Win32 icon.
- Implement Win32 platform functions.
- Fix build system for Win32.
- Add missing END_OF_MAIN().
- Remove GZip support.
- Fix data path in `make install'.