Add display modes 'pack', 'squish' and 'dense' to CanvasFeatures
Added display mode selection to CanvasFeatures context menu
removed unnecessary code from BlockBased.js and fixed checkbox error in CanvasFeatures context menu
make rect layout tweak its pitchY for squished mode, rename pack/squish/dense to normal/compact/collapsed
fixup
also modify the pitchX of the layout when in compact display mode
don't bother connecting mouseover events in canvastracks when in collapsed display mode
add layout options to release notes
don't let layout pitches round all the way to 0
make box glyph not clear its area if in collapsed display mode