Merge pull request #748 from RotaruDan/proposedFixes

Proposed fixes
Fixed minor bugs and added remove button in variables widget.
Now the navigation button show the initial scene correctly.
Added new notifications.
Added new notifications in camera error
Merge pull request #749 from gorco/improvs

Improvements in variables pane and navigation panel
Improves the RepositoryView with an InfoPanel.
Improves hit detection while a HiddenPanel is opened.
Other small fixes: notification text aliugnment, InfoEditionPanel typo, ScenesTableList thumbnails regeneration, etc.
RepositoryElements now are centered ion the screen.