Docstring refactor of core

Related to issue #25 and #19. All files in core now have docstrings in the numpydoc format along with some minor refactorings.

src/simudator/cli/cli.py

@@ -89,8 +89,7 @@ class CLI:
         self._print_list = []
 
     def run(self) -> None:
-        """
-        Run the CLI.
+        """Run the CLI.
 
         Put the user in an input loop where they can send commands to the
         program.