Fixes #887

- Only use navigation nodes to find the node at point
- adds a test for cascades
renames `Node >> atPosition:` to `Node >> navigationNodeAt:ifAbsent:`
Fixes #850 #851 #852 #853
Fixes HLDebuggerCodeModel >> doIt:
Expose `confirmationText` and `cancelText` in HLModalWidget
Fixes HLMethodsListWidget >> reselectItem:
Renames button label accessors in HLModalWidget
Fixes HLClassesListWidget >> renderItem:level:on: to force reactivation
of the class on click
Adds a css class to helios widgets
removes DoIt >> foo
Fixes #563
better background color for helios debugger header
Makes helios overlays transparent
faster transitions for modal windows
solid background for helios key binding helper
fixes #868
fixes #600
Fixes #539
helios tabs: do not append the tabs for each refresh
Avoids having several warnings in a row about unsaved changes