* Replace use of old term label with attribute
The specification has unified on the term attribute to describe
key-value pairs. There exist still many hold-overs of the use of the
term label. This updates those uses or deprecates exported types and
functions in favor of renamed forms.
* fix infinite recursion
* Remove backticks from attribute set docs
* Remove LabelFilterSelector entirely
* Remove Metadata.Labels instead of deprecate
* Update changelog with public changes
* Revert OC err msg
