The Stage is now implemented as a runtime-checkable Protocol.
Part of this led to the realisation that we can't create a DirectThingClient
based on a Protocol, only on a concrete Thing. While it might be
a good idea to address that in LabThings in due course, for now
we work around it by creating both a Protocol and a stub class. The stub class implements the protocol, and
can be used to declare a dependency.
I've now split the base camera code into a runtime-checkable Protocol
and a concrete base class (which is optional). This removes the requirement
for cameras to subclass `openflexure_microscope.things.camera.Camera`
and instead uses duck typing that should
work both statically and dynamically.
As part of this, I've moved the commonly-used dependencies
on the camera inside `openflexure_microscope.things.camera` for consistency, and to make it easy to update them if it changes in the future.
I've now defined parent classes for camera and stage, and depend only on those. This allows
proper typing while enabling the actual hardware
classes to be swapped.
The interfaces definitely aren't final - this is a first
draft, largely to enable me to test out the concept
of a configuration server.
