Easy history printing.
New PrintHistory.
Enhanced examples
Some tweaks in Logic.
Snake-Lemma example for modules
Updated submodule.
Merge branch 'master' of https://github.com/sebasguts/CategoriesForHomalg

* 'master' of https://github.com/sebasguts/CategoriesForHomalg:
  Updated submodule.
  Some tweaks in Logic.
Corrected typo
Added all files to deductive system.
Fixed filenames.
Snake-Lemma-Example over the integers
Installed automated propagation for deductive category.
Merge branch 'master' of https://github.com/sebasguts/CategoriesForHomalg

* 'master' of https://github.com/sebasguts/CategoriesForHomalg:
  Installed automated propagation for deductive category.
  Fixed filenames.
  Added all files to deductive system.
Family properties for objects
Deleted wrong declaration