Improve doc strings in the regression test framework.
* subversion/tests/cmdline/svntest/actions.py
(make_repo_and_wc): Mention that it makes a 'Greek Tree'.
* subversion/tests/cmdline/svntest/main.py
(run_command): Refer the reader to run_command_stdin() for details.
(wait_on_pipe): Add some documentation that was missing.
(spawn_process): Convert the plain comment into a doc string and document
the 'binary_mode' parameter.
(run_command_stdin): Document the 'binary_mode' parameter.
git-svn-id: http://svn.apache.org/repos/asf/subversion/trunk/subversion/tests/cmdline@888465 13f79535-47bb-0310-9956-ffa450edef68