Enhanced examples
Snake-Lemma example for modules
Merge branch 'master' of https://github.com/sebasguts/CategoriesForHomalg

* 'master' of https://github.com/sebasguts/CategoriesForHomalg:
  Updated submodule.
  Some tweaks in Logic.
Corrected typo
Snake-Lemma-Example over the integers
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