* install
  - make pperl suggested dependecies and automatic enable it.

* finalize SVK::Patch interface

* signal handling
  - SIGINT should be handled gracefully.

* path reporting
  - show paths in import and commit.

* better tree merger
  - Merge added directories.
  - Merge moved files and directories.

* checkout signatures
  - command to purge cache.
  - cache for modified files also, but the gain is marginal.
