OpenWarp

First major version increment. Adds:

• Preservation of warp history (/back, /warp stack) through server reload
• Allow warp sharing/"invites" via /warp share
• Add a Multiverse-2 destination type (ow:WARP)
• Allow players to set a home per-world
• Allow admins to move to other players' homes via /home NAME

There may be an issue with saving the warps.yml file; the bug is intermittent and difficult to reproduce, if it exists. See issue 26 for more info, or to report a problem.