Revision 1801942

On the 'shelve-checkpoint' branch: Prototype checkpointing.

Commands are:

    svn checkpoint save
    svn checkpoint revert
    svn checkpoint rollback NUMBER
    svn checkpoint list|--list
    svn checkpoints

* subversion/include/svn_client.h
  (svn_client_checkpoint_get_current,
   svn_client_checkpoint_save,
   svn_client_checkpoint_restore,
   svn_client_checkpoint_delete,
   svn_client_checkpoint_list): New.

* subversion/libsvn_client/checkpoint.c
  New file.

* subversion/svn/checkpoint-cmd.c
  New file.

* subversion/svn/cl.h
  (svn_opt_subcommand_t): Declare the checkpointing commands.

* subversion/svn/svn.c
  (svn_cl__cmd_table): Describe the checkpointing commands.

* tools/client-side/bash_completion
  (_svn): Add the checkpointing commands.