R3R 2.9.1

This is the last stable code before I started work on 2.10. It contains many improvements over 2.9: it's more stable and faster. On Unix-like systems, if you don't have the XDG directory environment variables set, the various cache and data files will be in different places. You should be able to just move the files from ~/.config (except for r3r.ini or reg.xml, depending on which settings backend you use) to ~/.local/share and from ~/.config/cache to ~/.cache.