Automatic merge of Transifex translations
* Drop obsolete PlaylistView.
Added TomahawkUtils::Queue enum.
* FlexibleView is becoming a ViewPage wrapper for ContextView.
Adapt to new FlexibleView API.
Don't replicate so much of TrackView's API in ContextView.
* Use existing 'changed' signal in PlaylistView.
Emit 'modelChanged' when underlying model changes in TrackView.
* Renamed FlexibleView to PlaylistViewPage.
Added ContextView::setTrackView, allowing you to replace the TrackView with your own implementation of it.
Inbox needs to set its own TrackView on ContextView.
Use ContextView's wrapped modelChanged() signal in PlaylistViewPage.
* Removed obsolete filtering via ViewManager / InfoBar.
Removed InfoBar entirely. Yes, this currently leaves Station-mode a bit, uhm, headless.
Removed obsolete TreeView, TreeWidget and TreeItemDelegate.
* Removed obsolete CheckDirTree.
Moved & renamed infowidgets/ to viewpages/
Style fixes in TomahawkWindow.
Removed obsolete PlaylistTypeSelectorDialog and NewPlaylistWidget.
Remove virtual keyword from some functions.

These functions are not overloaded at the moment in any child class but
some of them are called very often which adds a significant overhead. If
really needed they should be reverted to virtual when we actually
overload them.