add folder option to sidebar styling
remove whitespace
minimized folder keeps the gray color
use with with opacity instead of specific colors

toc-color-light is still in use elsewhere, so leaving it in
Merge branch 'master' into atc-sidebar-folder-styling

Conflicts:
	styles/variables.less
add explicit dependency for filtered-collection
Merge remote-tracking branch 'oerpub/atc-sidebar-folder-styling' into github

Conflicts:
	styles/workspace/sidebar.less
remove dangling merge conflict
Merge remote-tracking branch 'oerpub/dependency-for-filteredcollection' into github