Disallow new script with class_name or add_custom_type()

[Shadowblitz16]

Describe the project you are working on:
NetworkedTest

Describe the problem or limitation you are having in your project:
I don't want to accentually add a new script to one of my nodes.

Describe the feature / enhancement and how it helps to overcome the problem or limitation:
Disallow new script with nodes created from node browser and only have extend script

Describe how your proposal will work, with code, pseudocode, mockups, and/or diagrams:
This makes sure people aren't attaching scripts that aren't intended for the object.
If they want to attach the script they have to extend it

If this enhancement will not be used often, can it be worked around with a few lines of script?:
It would be used in node inheritance and type safety

Is there a reason why this should be core and not an add-on in the asset library?:
It makes work flow better and more stable (basicly your not breaking things)

[Shadowblitz16]

in favor of this I'm closing #2612
and a future suggestion