Greasemonkey 3.12 Release

The entire list of bugs handled in this release is also available via the 3.12 milestone on GitHub. Note that as always it takes some time for Mozilla to review the new version.  If you're interested in staying on the bleeding edge, try installing the development channel beta release.  If you are using this version and notice problems, it's best to log an issue or let us know at greasemonkey-dev (and be clear that it's with this version).

Fixed bugs:

• Repair rare breakage in GM_getValue/GM_setValue. (#2506) 

New features:

• Migrate existing scripts to a WebExtension (for Firefox 57+) compatible data storage location.  (#2551)