Make creating type classes lazy

[jcklie]

Is your feature request related to a problem? Please describe. Right now, when loading a typesystem, all Python classes representing types in the type system are created, whether they will be used later or not. This is slow for large type systems.

Describe the solution you'd like Make it possible to create a type class when creating an annotation of that type for the first time.

[reckart]

Is this a performance optimization?

[jcklie]

Yes

[jcklie]

Should be ok done.