Rework: Decorator pattern module construction

[Harrison-Oatman]

Objective:

Use decorators to simplify the specification of a custom pattern module. Right now, the user needs to have too much knowledge about PyCLM to implement a custom pattern module. For example, the users has to make three methods that each take specific inputs that have to be passed along to the base class. Also, the user has to return an AcquiredImageRequest to ask for data -- this is an awkward thing to do, especially in the context of a script.

Potential features:

• model parameters as the only arguments to init
• No model.initialize(), just specify what channels need to be requested
• Ideally, a more streamlined way to specify which channels to segment or use as raw data
• generator function should NOT require a datadock