prepare for release of 2.0.16 | package party
Fix hasDateProperty()

To our shame we didn't test this when adding it. The date_properties array is an array of properties, not an indexed array of values. So use the correct in_array().
Make the SwatDetailsViewField's header title come from a method and update the vertical field to use it.

This fixes two issues in the SwatDetailsViewVerticalField header:
 * It now respects the show_colon property.
 * It now shows a &nbsp; when no title is set, just like SwatDetailsViewField
Add docs.
Merge pull request #23 from isaacgrant/show-colon

Make the SwatDetailsViewField's header title come from a method
Merge pull request #22 from isaacgrant/fix-has-date-property

Fix hasDateProperty()
Kill no longer necessary PACKAGE_ID

:skull: death to old cruft.
As no active package uses the package_id anymore, remove it completely.

While here also remove dead addTangoAttribution() method nothing calls anymore.

This should require a minor version bump as it breaks the api.
Bump the package minor version as dropping the PACKAGE_ID constant and use breaks the public API.