Add SystemBundle

[AndreaCatania]

Bound with #39

The SystemBundle is a collection of Systems that allow to add Systems, to the pipeline, in bulk. This is useful to speed-up and make easier the pipeline composition.

Some example are:

• RenderingBundle
• PhysicsBundle
• ....

Feedbacks

• I can override or add to a bundle (Bundle MyRigidBody = Godex.RigidBody & SomeComponent)

Notes

• The SystemBundle just contains actual Systems that can still be added one by one.
• The SystemBundle is just an Editor concept so it doesn't bloat the actual godex::pipeline core.

[AndreaCatania]

An additional idea could be allow the SystemBundle to have extra information: like the Pipeline position (or the pipeline sub group) per each system. In this way we could have 1 bundle for each feature; that is able to register the systems sparsely in the pipeline.

This should improve the pipeline creation drastically, since the user would need to add just few bundles (one for each feature he wants to use).