comment parts in the OPF
add support for book with overridden titles
increase the drop area on nodes
cloning a book keeps the overridden title (or original if it was not overridden)
forgot to finish fixing the bigger dropzone
reduce number of reparses when dropping content
Merge remote-tracking branch 'origin/atc-fixes' into testing

Conflicts:
	scripts/views/workspace/sidebar/toc-branch.coffee