rework toolbars to be RB3 visually compatible with popups placed below the buttons and themed accordingly.  Also taken the opportunity to redo the right toolbar to fit on one less line since this sidebar is often used with lyrics which is wider and thus offers more space.  Preliminary views button created for library source although not connected as yet.  issue #230
Merge branch 'master' of https://github.com/fossfreedom/coverart-browser