Now using Butler for providing downloads and updates

Still getting used to distribution via itch.io.

If all goes well, the zip files I uploaded manually will today be replaced by builds created with itch.io's Butler tool. This will make future patches easier.

The new Linux download will also include the 32 bit binary, and will be stripped off the unnecessary Windows .dll files.

The new Windows download will be without the Linux binaries. (The Windows binary is a 32 bit file, but runs on 64 bit systems, too.)