[Core] Plugin can be defined through annotations?

[MatteoJoliveau]

To be more flexible, a plugin could be written by annotating its main class, for example in the following way:

@Plugin("test_plugin")
public class TestPlugin {

    @Start
    public void aMethodThatStartsThePlugin() {
        //stuff
    }

    @Stop
    public void aMethodThatStopsThePlugin() {
        //stuff
    }

}

[MatteoJoliveau]

Done, removed any functionality outside of loading, delegating actual plugin logic to whatever the user may want since she's now able to ask for plugins by their interface/supertype. No need to have start/stop/execute logic anymore