implemented single-column layout-switch, and added a toc-icon to regain space.
Merge branch 'nevir' into feature-collapsible-columns

Conflicts:
	lib/styles/default/style.css
removed changes related to testing purposes only
updated layout-switch implementation
Merge branch 'feature-collapsible-columns'

Conflicts:
	lib/styles/default/style.css
	lib/styles/default/style.sass