Merge pull request deanishe#16 from pyrho/feat/sort-by-mru

feat: sort tabs by MRU by default

Merge pull request deanishe#16 from pyrho/feat/sort-by-mru

feat: sort tabs by MRU by default

Don't split environment variables

Add support for other Firefox browsers. Closes deanishe#2

Added support for Firefox Nightly and Developer Edition.

The workflow detects which browser it's connected to and opens URLs in
that browser, and activates that browser when a tab is activated.

Update doc links

Document "Current Tab Actions"