hide vacant tags


This patch prevents dwm from drawing tags with no clients (i.e. vacant) on the bar. Moreover, clients assigned to all tags ("tag 0") do not count towards each individual tag.

It also makes sure that pressing a tag on the bar behaves accordingly by not reserving reactive regions on the bar for vacant tags.

It also stops drawing empty rectangles on the bar for non-vacant tags as there is no need anymore to distinguish vacant tags and it offers a more visible contrast than if there were filled/empty rectangles.