Tagging release 0.6.4
Tagging release 0.6.3
Tagging release 0.6.2
Tagging release 0.6.1
Tagging release 0.6.0
Tagging release 0.5.5
update for 0.5.4
Tagging release 0.5.3
Tagging release 0.5.2
Merge remote-tracking branch 'origin/master' into 0.5.x-dev