Refactored navtree mixins. As discussed in #33, ToC numbers are now placed in the left margin so that text is aligned across line breaks.
Decreases gutter between codenumber and title in ToC ever so slightly.
Seperated touch sizing from default sizing as requested in #33. Rob's fat fingers will be pleased :)
Fixed problem where ToC children received touch-sized indent in desktop layout.
Moved toc into its own partial.
Reduced approximate codenumber width.
Ellipsis no longer show on icon-only buttons in firefox, as reported in #33.
Reduced ToC child segment height on desktop, as requested in #33.
Increased margin between sections.
Merged feature/ui-spacing with develop.