- a rework of doc layout and nav:
  - reduce the real estate for the top nav; move the search box
    into the top yellow box, close in space
  - use a new CSS/js approach such that the top toolbar freezes from
    scrolling at the top of the page.  The left nav scrolls independently
    of the content pane so that the local contents remain visible regardless
    of scrolling.   this approach is disabled on mobile where the dual scrollbars
    may be cumbersome (overall the site is not well designed for mobile).
- Fixed a few edge cases which arise in the so-called "row switch"
scenario, where an INSERT/DELETE can be turned into an UPDATE.
In this situation, a many-to-one relationship set to None, or
in some cases a scalar attribute set to None, may not be detected
as a net change in value, and therefore the UPDATE would not reset
what was on the previous row.   This is due to some as-yet
unresovled side effects of the way attribute history works in terms
of implicitly assuming None isn't really a "change" for a previously
un-set attribute.  See also :ticket:`3061`. fixes #3060
Merge branch 'master' into rel_1_0