Module IPlugin

Defines the basic interfaces for a plugin. These interfaces are inherited by the *core* class of a plugin. The *core* class of a plugin is then the one that will be notified the activation/deactivation of a plugin via the ``activate/deactivate`` methods.

For simple (near trivial) plugin systems, one can directly use the following interfaces.

When designing a non-trivial plugin system, one should create new plugin interfaces that inherit the following interfaces.