Greasemonkey 3.4 release

The entire list of bugs handled in this release is also available via the 3.4 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).

Feature enhancements:

• Added features to GM_openInTab. (#2257)
• Improved performance and memory efficiency. (#2225, #2237)
• Remember user script sort order. (#2128)

Fixed bugs:

• Work around a Firefox bug that broke GM_openInTab when e10s is not enabled. (#2234)
• Fixed a bug in the "view script source" feature preventing the tab from opening correctly. (#2202)
• Correctly handle uninstalled scripts and user @match preferences through Sync. (#2186, 2188)
• Improved the behavior of cloneInto to work in more cases. (#2070)
• Scripts that are run-at document-start will run on about:blank. (#2041)