Summary: a parent class for the "controller" object required for all simulations.

The Control object sets up and controls simulations. Every simulation must have one Control subclass. The user subclass of Control should set up the simulation in the "init" method.

The Control class also acts as the main interaction between the user and the breve environment itself. It provides access to elements of the user interface, for example, so that the user can add menus and other interface features from inside simulations.

Because the breve engine is designed to run on a variety of systems, there are varying levels of support for some of these features. In some cases, the features won't be supported at all on a system. A background daemon written to use the breve engine, for example, will not place a dialog on the screen and wait for user input.