ViewPresenter option to only generate views during run-time

[patrik-u]

Add an option to have the view-presenter only generate views during run-time. Suggested solution:

If OnlyGenerateDuringRuntime bool is set, then 1. still generate the views in editor but destroy them after initialization, this makes sure assets are loaded and errors are caught. 2. During run-time generate the views when the view-presenter awakes.

The reason for this feature is to improve the workflow so changes in XML don't lead to the scene having to be merged.