New feature:
- New Transparent tag visual (grey border & text, white bg),
- By default, newly created kanban tags are transparent,
- Tag's colorpicker has now a 'Hide in Kanban' checkbox,
to select the transparent color.
Toggling off 'Hide in Kanban' sets the color of the tag as follow:
- Previous color, if 'Hide in Kanban' was toggled on on the
same formview session.
- Color 1 (dark orange), otherwise.