[PATCH] Fix python bindings for svn.ra.lock()

Hi,

The attached patch fixes the Python bindings for svn.ra.lock().

[[[
Fix Python bindings for svn.ra.lock().

* subversion/bindings/swig/include/svn_containers.swg: Add Python
  typemap for apr_hash_t *path_revs.

* subversion/bindings/swig/svn_ra.i
  (svn_ra_lock_callback_t): Add Python typemap

* subversion/bindings/swig/python/libsvn_swig_py/swigutil_py.c
  (svn_swig_py_path_revs_hash_from_dict): Add function for converting
  from dictionaries to apr_hash_t * mapping paths to revnums.
 
  (svn_swig_py_ra_lock_callback): Add Python wrapper for
  svn_ra_lock_callback_t

* subversion/bindings/swig/python/libsvn_swig_py/swigutil_py.c
  (svn_swig_py_path_revs_hash_from_dict): Add prototype.

  (svn_swig_py_ra_lock_callback): Add prototype.

* subversion/bindings/swig/python/tests/ra.py
  (test_lock): Add test for svn.ra.lock()

]]]

svn.ra.lock()'s test doesn't work completely yet, because it fails to
retrieve a username from the auth baton without evil hacks. I hope to
address that in my next patch.

At some point, the various functions that convert dictionaries to
apr_hash_t * should probably refactored to use a common helper function.

Cheers,

Jelmer