fix MPS-18185 (rootCell can be null)
TreeHighlighter.dispose(): addListener => removeListener
fix MPS-18180 [build:MPS-129.189] Already disposed: Project (Disposed) NYoSh: Already disposed: Project (Disposed) NYoSh
move gen priorities editor to external dialog
gen priorities render:
hide fully unchecked
hide children for checked node if they all checked
hide checkboxes
fix MPS-17993, MPS-17908
Merge remote-tracking branch 'origin/master' into 3.0/mikev/test