remove most 3.10 bw compat
Related to #3799117.
The boxes and entityvcomponent objects cannot really be removed as they
are still used throughout the code base (and possible cubes).
This may be caused by a non-working deprecation and needs some more
work.
Document: cubicweb-doc
Title: CubicWeb documentation
Author: Logilab
Abstract: Some base documentation for CubicWeb users and developpers
Section: Apps/Programming
Format: HTML
Index: /usr/share/doc/cubicweb-documentation/index.html
Files: /usr/share/doc/cubicweb-documentation/*.html