Stop 'svn copy -rBASE wc_path1 wc_path2' from failing.  This isn't the ideal
answer since it will contact the repository, but presented the least amount of
change given that we're on our way to 1.0.

* subversion/libsvn_client/copy.c
  (repos_to_wc_copy): Updated this function to now take a WC path as a
  parameter, to allow keywords like BASE, PREV, and COMMITTED to be resolved.
  Renamed src_url parameter to src_path_or_url to reflect the change.

  (setup_copy): Stop referring to parameters as being URLs.  Instead, indicate
  whether or not we want to go to the repository for the source or
  destination.  Also, stop resolving a source path to a URL in the repos->wc
  case.  Instead, let repos_to_wc_copy() resolve it, since it needs to wc path
  to resolve the revision parameter correctly.