Problem: API generation no longer done here (it's in ztools)

Solution: remove this from mkdoc script
Problem: selftest code uses 'tmp' as variable name

And has other style issues. Solution: fix these.
Regenerated man pages:
Merge pull request #853 from hintjens/master

Minor maintenance
Dir patch does not duplicate delete patches

Problem: The zdir_patch object does not duplicate a patch that is
a delete operation. The duplication method requires that the file's
digest is not NULL, but a delete operation will not have a file to
read to calculate the digest.

Solution: Added a test for the operation type before the zdir_patch
object is destroyed for having an empty digest.
Merge pull request #854 from danriegsecker/master

Dir patch does not duplicate delete patches
Ref #855
Merge pull request #857 from keent/master

Ref #855
Problem: should be possible to clear cached file digest on file instances

Solution: call zdigest_destroy on zfile_restat
and inline zfile_close in zfile_digest

Other solutions are possible:
* provide explicit method to clear the file digest
* don't cache the digest
Merge pull request #858 from skaes/zfile_restat_should_reset_file_digest

Problem: should be possible to clear cached file digest on file instances
Problem: make debug does not work on OS X

Solution: call proper libtool
Merge pull request #859 from skaes/master

Problem: make debug does not work on OS X