Add Import/Export Feature

[XjSv]

It would be nice to be able to export all configurations and import them in a different instance or simply being able to take a backup.

[XjSv]

As of commit: 4552815 the Export/Import feature has been added.
New build coming soon.

[XjSv]

After testing it seems that in Firefox the file picker input does not work. This seems to be a long standing bug in Firefox.

• https://bugzilla.mozilla.org/show_bug.cgi?id=1292701
• https://bugzilla.mozilla.org/show_bug.cgi?id=1366330
• https://bugzilla.mozilla.org/show_bug.cgi?id=1411000
• https://bugzilla.mozilla.org/show_bug.cgi?id=1384190
• https://bugzilla.mozilla.org/show_bug.cgi?id=1384684

[XjSv]

Moved the import/export feature to its own options page as of commit 82fe4ee.
This way we can bypass the Firefox popop and file input bug.