Merge branch 'ne/rev-cache' into pu

Merge branch 'ne/rev-cache' into pu

* ne/rev-cache:
  support for path name caching in rev-cache
  full integration of rev-cache into git, completed test suite
  administrative functions for rev-cache, start of integration into git
  support for non-commit object caching in rev-cache
  basic revision cache system, no integration or features
  man page and technical discussion for rev-cache