Make "svn revert" not sleep for approximately 1 second per
path named on the command line; instead, do the "sleep for
timestamp integrity" once at the end of the operation. See
brief discussion in dev@subversion starting at message 48749.

* svn_client.h
  (svn_client_revert_list) New function.

* revert.c
  (revert_1) New function, doing what svn_client_revert
  used to do apart from the final sleep.
  (revert_n) New function, calling revert_1 multiple times.
  (svn_client_revert) Eviscerated, so that it now just calls
  revert_1 and then sleeps.
  (svn_client_revert) Now takes a list of paths, calls
  revert_n and then sleeps.

* revert-cmd.c
  (svn_cl__revert) Call the new svn_client_revert once,
  instead of the old one many times.