Add long option support and improved usage/help to svnserve.
Add long option support and improved usage/help to svnserve.

* subversion/svnserve/main.c

  (svnserve__options): New struct with all svnserve options.

  (usage): Show short message instructing the user to use --help.

  (help): Show full usage with all options listed and described.

  (main): Use the new long options struct. Call usage for usage
  errors and help for the --help option.


git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@847367 13f79535-47bb-0310-9956-ffa450edef68

wbond/subversion,YueLinHo/Subversion,YueLinHo/Subversion,wbond/subversion,YueLinHo/Subversion,wbond/subversion,YueLinHo/Subversion,YueLinHo/Subversion,wbond/subversion,wbond/subversion,wbond/subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,wbond/subversion