Inline Searchview

This task split the searchview in two parts: SearchView and SearchViewDrawer.  The drawer is displayed inside the main view and the searchview stays in place.

Because of this, other large changes have been made: 
* the drawer has been redesigned, 
* the Custom Filter widget has been split in two (Custom Report and SaveCurrentFilter), 
* the main view is now scrollable, so the UI stays in place and only the view can change
* The text 'Group By...' has been changed into 'Group By' (most addons had to be modified)
* bootstrap classes are used when it makes sense (for example, badge)
* the left menu is also scrollable (separately from the main view)
* the view_manager_body is positioned with 'absolute' => might have some unwanted consequences if views try to use position coordinates

It is likely that some stupid bugs have been introduced, and also possibly many usability issues/questions have to be resolved in the future. 

(task Inline searchbar, in project RD Framework)