backport support for testing against storages other than `DemoStorage` (r80357:80358) from Zope 2.11

- Moved exception MountedStorageError from ZODB.POSExceptions
  to Products.TemporaryFolder.mount (now its only client).

- LP #253362:  Moved Zope2-specific module, ZODB/Mount.py, to
  Products/TemporaryFolder/mount.py (its only client is
  Products/TemporaryFolder/TemporaryFolder.py).

- Removed spurious import-time dependencies from
  Products/ZODBMountPoint/MountedObject.py.

        header if it is already present - this can make cache configuration
        difficult. (merged 99493)

        using CRLF as requested by RFC 2616. (merged 90980, 92625)

over indexes if the result set is already empty.

- Launchpad ##332168: Connection.py: do not expose DB connection strings
  through exceptions

LP/#143873: Fixed problems when no HTTP_ACCEPT_CHARSET is in the request. This required an update of zope.publisher to 3.3.3.

  from a meta-equiv header

Use a layer to load the CA (we need the container handlers).

Replace messy tests with cleaned-up versions from trunk.

o This move breaks an import cycle in third-party code which avoids imports
  from 'Globals.'
  
o Leave the class importable from its old location without deprecation.

- The level < 0 case is basically the union of all searches for levels 0
  through to max. Just call search() for each level and use multiunion on all
  the results.
- Shorten the 'no-such-path' detection to one test.

into CVS trunk 8 years ago..

'tal:on_error' handler has attributes visible to restricted code.

HTTP spec (RFC 2616).

  tests and implementation for guarded_zip (RestrictedPython).