Fix for 464+tape adapter (rebuild)

Just needed a bit of delay added after the LOADER to give the 464 time to stop and start the tape motor.

Also works around a mingw filename issue that broke the previous version of this release.

Fix for images with non-standard GAP#3 values

Fixes Pinball Dreams (properly, this time!)

Fix for images with unformatted tracks

Some disc images include zero-length tracks (basically meaning unformatted); the tool would fail when trying to read zero bytes from the image.

Thanks to Stefan for letting me know about this bug and providing an example image for testing.

Resurrected Windows build

Finally got around to implementing a CI build using github actions. Hopefully this one won't go under like the last two I used.