Merge pull request #180 from charlylima/bookmarks-charly

pull charlylima:bookmarks-charly to csete:bookmarks
Undo file mode changes.
Add Selection of Tags to Add-Bookmark Dialog.
Add possibility to change Tags by selecting from a List of Tags in Bookmarks-List.
Therefore move taglist into its own class 'bookmarkstaglist'.
Convert 'bookmarks' class into a singleton class because you can not send qt-signals without an object, every single member was static before.
merge csete gqrx bookmarks-branch

Merge remote-tracking branch 'upstream/bookmarks' into bookmarks-charly
deleted: bookmarks.csv