Breaking up https://github.com/backdrop/backdrop-issues/issues/3639 into some easier chunks.
- [x] at
admin/content/bookchange the tab title to "Manage books"
- [x] fix the breadcrumb when at
- [x] Remove the Outline tab on nodes (
node/%/outline). We have a "Book outline" vertical tab on the node edit with the exact same form.
- [x] add a "Remove from book outline" link to vertical tab on node edit.
- [x] add a "Reorder book pages" link to vertical tab on node edit.
- [x] Make "Content type for child pages" into select list.
- [ ] fix entity cache issue when removing node from book outline