Upgrade sagenb to version 0.10.7.1
Merge branch 'ticket/14330' into tip
Merge branch 'ticket/14482' into tip
remove workaround for sagenb pull request 84 (#14273)
Merge branch 'ticket/14273' into tip
Merge branch 'ticket/14482'
Merge branch 'ticket/14482'
Merge remote-tracking branch 'trac/public/sage-git/ticket/14482'
Merge branch 'u/saraedum/ticket/14482' of ssh://trac.sagemath.org:2222/sage into HEAD
Merge branch 'ticket/14482'
Merge branch 'ticket/14482' into public/sage-git/master
Merge branch 'ticket/14482' into public/sage-git/master
Merge branch 'ticket/14482' into public/sage-git/master
Merge branch 'u/ohanar/build_system'

Conflicts:
	build/pkgs/sagenb/SPKG.txt
	build/pkgs/sagenb/checksums.ini
	build/pkgs/sagenb/package-version.txt
	src/sage/doctest/forker.py
Merge remote-tracking branch 'origin/build_system' into public/sage-git/master
Merge branch 'ticket/14482' into public/sage-git/master
Merge branch 'ticket/14482' into public/sage-git/master
Merging Sage-5.12.beta5, newest dev scripts, and the doctest fixes.
Remove obsolete spkg installed markers.
Makefile target to download upstream sources.

Original author is Robert Bradshaw, moved to our git repo from
https://github.com/robertwb/sage/commit/ff4568367a0c58fe74cf82b450ca43c592e588aa