Avoid calling recolorRows() for each closed node in a tree_editor.

Together with a slowness probably due to recent update to jquery, this
resulted in terrible page tree rendering times (around 40s for 400 pages).
Instead of simulating a click on the row, just call the row handler directly
and recolor everything afterwards.
Also speed up recolorRows() x5 by rearranging and caching some selector results.
Add missing row recoloring after expanding items with keyboard.
Merge remote-tracking branch 'upstream/next' into next