Open Bookmarks in Tabgroup troch igorlogius

Adds a context menu entry on a bookmark folder which allows to open all containing tabs into a tabgroup with the same name as the folder. Right click on a bookmark folder and in the context menu click on the "Open Tabgroup" entry

If a tab group with the same name already exists, the "Replace an existing tab group" option decides what happens: by default it is closed and reopened fresh; when turned off, the existing group is kept and only bookmarks whose URLs are not yet open in that group are added to it.

The tabs in the group are ordered the same way as the bookmarks in the folder.