Created a V2 nav tree list widget, to encapsulate CSS, HTML, and assets. Updated various pages of the UIZE site to use the new widget for contents trees.
Moved the tree test data to under the Uize namespace, so it can be used in visual tests for the nav tree widgets.
More stylistic lightening.
Created a V2 nav tree menu widget and updated the site menu for the UIZE site to use it.