Move document sidebar entries extraction to document.View
This way other modules can benefit from the same logic. Also make use
of the sidebar.getSidebarMenu method so that getMenusForScope is no
longer specific to full menu's.
Patch by: Sverre Rabbelier
Factor out sidebar entry construction
This makes it possible to reuse this logic in other modules as well,
preventing code duplication. While at it, move additional_sidebar
merging before the other entries (additional entries should go first,
since the other entries are mostly dev-only etc).
Patch by: Sverre Rabbelier