Added main methods to some classes for testing purposes.
Minor code refactoring simplifying it for efficiency and clarity.
New:
Action, (refactored) ActionManager, Character,(refactored) Character_Sheet,
 (refactored) Enemy, (refactored) Player, Stat_enum.

Removed:
Char_sheet, CharacterManager, Controlled.

ActionManager was refactored; CharacterManager was merged into it because
it has related functionality such as managing the game in a client-server
approach, later explained in more detail.

A Character class child to Entity, parent to Player and Enemy was added to
separate between living and non-living entities.

Character_sheet was rethought. It now works as a base-stat reference for
the character. Leveling and items will add to the total modifier.
Stat_enum was added to help in method simplicity.

What is intended:

Trying to create client-server relationship by separating the
ActionManager from the InputManager.

The InputManager queries in one thread (client) input, in the other
thread (server) actions created by the different clients are added to
the ActionManager stack of actions, executing them in order.

ActionManager now controls both the CharacterList and the Actions.
This is a set up designed to take the place, in the near future,
of the server.

InputManager gets, formats, creates actions and pumps them to the
 ActionManager.