Adds new formating options for tasklist:
Adds new formating options for tasklist:

* adds markup_* options for formatting of the taskname
* adds suport for pangomarkup in markup_*
* adds support for uniform distribution of taskboxes sizes

Closes #1155

tych0/qtile,flacjacket/qtile,zordsdavini/qtile,ramnes/qtile,frostidaho/qtile,cortesi/qtile,tych0/qtile,cortesi/qtile,qtile/qtile,flacjacket/qtile,soulchainer/qtile,zordsdavini/qtile,ramnes/qtile,frostidaho/qtile,qtile/qtile,soulchainer/qtile