version 0.5.4 released

From the release notes:
This release has come about for two reasons. First there
have been significant changes to Grok, as can be observed
in the change log. However, more importantly, there is
going to be a lot of old code ripped out of Grok in the
weeks to come, so it seemed a good idea to make a code
capsule release before doing that. This release has thus
been named the "Deadwood" release, but it nonetheless does
contain a lot of low-level improvements as well, and
reintroduces parsing functionality.