First version of new history.
Some more work on new history
Update - squash later
Files for creating more history functions.
Some more history with objects.
Merge branch 'master' into history_devel

* master:
  Some more history with objects.
  Files for creating more history functions.
  Fixed example.
  Eval is now evaluation, and does store its values weak.
  Two algorithms for snake lemma.
  Updated submodule.

Conflicts:
	gap/DeductiveSystem.gi