intercept shift/ctrl double-clicks in tables
extended double click functionality in tables
close view when closing last sub-view unless this view is the last view
added new user setting: window/hide-subview (hide subview titlebar if there is only one subview in the window)
made double click actions in tables configurable
replaced the signal/slot user settings update with a regular function call
replaced regular function call from SubView to View with signal-slot-connection
Merge branch 'double'