In the intervening 8 years since there was last activity in this issue, zlib 1.2.11 has been released and probably has even more new features.  However, I think rather than looking for new features to implement, we should create specific issues to implement new features as use cases for them come up; chances are, some of these have already happened without reference to this isuse.  As such, I'm going to go ahead and close this issue.