* add: linter, type check, rework transitions

This commit introduces the following changes:
  - It adjusts the naming to fit to the new notation in the latests
    version of the paper.
  - It adds a linter configuration for pylint, taken from the google
    style guide and addresses all issues raised by the linter.
  - It adds documentation and rephrases the docstrings in google style
  - It adds type annotations and adjusts all types to enable type
    checking. This includes a new type for GTA transitions.
 - It adds printing of the minimal reach times 

* add: github actions CI pipeline is added

On pull request, each PR needs to pass the unit tests on all supported
python versions and pass linter as well as type checks

* update and improve Docker image

The Docker image has been updated to use the slim base image and the
.dockerignore ignores all unnecessary files.

* rewrite benchmark instructions & add missing files

The benchmark instructions have been updated and all uppaal files that
are currently presented in the paper are added.