(Merged from 3.7 branch.)

- References to headers now involve the package names.

- The zpkg support files have been moved to the top-level directory,
  and the releases/ tree has been removed.  The resource map and
  configuration file have been combined now that zpkg allows that.

- The scripts are now all located in src/scripts/ in a checkout.

- Scripts that were imported in the tests have been split into library
  and script components; the library portions share name of the
  script (in order to reduce changes).  The library portions may not
  be used as scripts directly.

and include that in the ZODB project.  While we're at it,
include zope.testing too, as zope.interface depends on that,
and we had copied zope.testing.loggingsupport.py into ZODB
earlier anyway (and delete that unique copy here now).

This also merges some changes made to the ZODB copy in
Zope3 back into ZODB.