Fix documentation building.
prepare for 1.7.1 release
Prepare for 1.7.0 release.
Prepare for 1.6.0 release.
update version for next release
Prepare for 1.5.1 release.
Prepare for 1.5.0 release.
tagging 1.4.1
belated tagging of 1.4.0
tagging 1.3.2