chore(navigation): move features to diagram-js

This commit moves the navigation features from bpmn-js to diagram-js so
that they can be reused in other modeling / viewer tools.

Related to #124

BREAKING CHANGE:

Navigation features have been moved to diagram-js. If you use them in
custom bundles, update their location accordingly:

bpmn-js/lib/features/movecanvas -> diagram-js/lib/navigation/movecanvas
bpmn-js/lib/features/zoomscroll -> diagram-js/lib/navigation/zoomscroll
bpmn-js/lib/features/touch -> diagram-js/lib/navigation/touch