svnauthz: improve help output.

The original motivation was that 'svnauthz help accessof | head -n2' listed
just two options, giving no indication that there are several others.

* tools/server-side/svnauthz.c
  (cmd_table."accessof", options_table): Improve various help strings.

git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1511272 13f79535-47bb-0310-9956-ffa450edef68
Add new regression test for a bug in 'svn diff -rPREV' with mixed-rev WCs.

* subversion/tests/cmdline/diff_tests.py
  (diff_prev_copy_in_mixed_rev_parent, test_list): New test.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1511273 13f79535-47bb-0310-9956-ffa450edef68