RMenu 4 and RMenu X21 Public Preview Release

I have decided to finally release preview versions of the next RMenu versions, RMenu 4 and RMenu X21.

These are not the final product, so they may have bugs. If you find any bugs while using these Public Preview versions, then you should probably report them on the RMenu 4 and RMenu X21 Public Preview page.

Hopefully, the release of these Public Preview versions will allow people to have a head start with RMenu 4 and RMenu X21 program development, as well as help make the eventual Release versions even better.