Maintenance release:
- Add sourcemap files: browser-polyfill, purify (issue #149, #104)
- Disable debug logs and fix error getting host when showing contextmenu (issue #157)
- Fix errors being logged when sent messages have no receiver
- Fix column visibility list not showing active columns
- Fix error adding MutationObserver to framesets (#153)
- Update Russian, Korean and Greek translations (#113, #132, #135, #158, #159)