(Collector #2248)

- minor code cleanup for handling wrong index names

The splitter is now aquired from the used vocabulary.

'Authenticated' role from the list of local roles that can be given
to the selected user.

Allow setting of individual permissions to fail, and note that failure in the message screen.  Otherwise, faulty __ac_permission__ information can prevent changes to security.

WebDAV to be turned on or off.  It defaults to the same access as
"Access contents information", the old controlling permission.

- Updated parameter declaration style.

- Used casts to PyCFunction where the function signature is compatible.
  I don't like this but it retains all current behavior.  I see a potential
  for segfaults.

- Removed ASSIGN macros, never used.

- Changed empty parameter list to "void".

- Removed the ASSIGN macros, which are never used.

- Removed the unused functions _PER_RETURN and _PER_INT_RETURN.

- Removed a dereference operation whose result is never used.

- Changed empty parameter list to "void".

- Put inline assignment in parantheses.

- Added parentheses to inline assignments.

- Removed the unused function "Twople".

- Unnecessarily initialized "iv" of BTree_ini().  (Compiler isn't smart
  enough to see that "iv" is never used uninitialized.)

- Added curly braces.

- Removed unused var "v" from BTree_setstate.

- Used "void" in place of empty parameter lists.

imported rather than silently ignore the test.

Update a comment describing the usage and basic API.

One for non-Zope use, one for pre-2.4 Zope use, and one for Zope 2.4+ use.