Focus on page load using the full power of CSS selectors

Limiting only to ids is annoying for elements without an id.

Heuristics could be added to support the old style id-sans-leading-hash,
but few extensions seem to use the Focus parameter or focusElementById()
directly.  Dropping support and moving to standard selector notation is
cleaner.
Refocus the new CF value name input after adding one

This helps greatly when adding multiple values in a row.

I thought we had this tiny feature in a previous version, but either it
was removed or I was simply dreaming.
Merge branch '4.2/focus-new-cf-value'