Make all commands provide a brief description of themselves in help output,
and consistently tell users where to find the program version.

Undo a change made back in 2004 (r851470) to make 'svn' show its version
number in help output. That behaviour was not carried over to other commands
and hence inconsistent. Since r860375 the --version option is prominently
documented in the main help text of many commands, and as of this commit
that is done consistently across all commands.

* subversion/svn/help-cmd.c
  (svn_cl__help): Don't show the version number in help output, instructing
    people to use the --version option is enough.

* subversion/svnadmin/svnadmin.c,
  subversion/svnauth/svnauth.c,
  subversion/svndumpfilter/svndumpfilter.c,
  (subcommand_help): Describe program's purpose in help output.

* subversion/svnlook/svnlook.c:
  (subcommand_help): Describe program's purpose in help output and mention
   the --version option in the main help text.

* subversion/svnmucc/svnmucc.c
  (usage): Describe program's purpose in help output and mention the
    --version option in the main help text.

* subversion/svnrdump/svnrdump.c,
  subversion/svnsync/svnsync.c:
  (help_cmd): Describe program's purpose in help output.

* subversion/svnserve/svnserve.c,
  subversion/svnversion/svnversion.c:
  (help): Describe program's purpose in help output and mention the
    --version option in the main help text.

* subversion/tests/cmdline/getopt_tests.py
  (rep_lines_res): No more need to substititute version number in 'svn help'.

* subversion/tests/cmdline/getopt_tests_data/svn--help_stdout,
  subversion/tests/cmdline/getopt_tests_data/svn_help_stdout:
   Adjust expected output.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1522518 13f79535-47bb-0310-9956-ffa450edef68