v3.3.0

• big re-write on how cellHeight() works. you can now call it at any time (not just grid init options) including switching to 'auto' or other modes on the fly.
• fix cellHeight:auto now keeps cell square as window resizes (regressing from 2.x TS conversion). Utils.throttle() works better too (guaranteed to be called last event)
• new cellHeight:initial which makes the cell squares initially, but doesn't change as windows resizes (better performance)
• new grid option cellHeightThrottle (100ms) to control throttle of auto sizing triggers
• fix 1600 height too small with cellHeight:auto loading in 1 column. Now detect we load at 1 column and size accordingly (default 'auto' could make big 700x700 cells, so explicit px might still be wanted)
• fix 1538 loading nested into small size and sizing back up
• fix 1604 nested grid resizing fix
• fix 1599 H5 resize from left side can move item right