Add FreeCAD.getAddonRegistry() function for runtime addon introspection.
Changes to addon_loader.py:
- Add contexts field to AddonManifest for tracking context IDs
- Add register_context() method for addons to declare contexts at runtime
- Add contexts() method returning {context_id: [addon_names]} mapping
- Parse <contexts> element from <kindred> in package.xml
- Add getAddonRegistry() function returning the registry singleton
Changes to Init.py:
- Expose getAddonRegistry as FreeCAD.getAddonRegistry after loading
Usage:
registry = FreeCAD.getAddonRegistry()
registry.get('ztools') # AddonManifest for ztools
registry.loaded() # list of loaded addons
registry.is_loaded('silo') # True/False
registry.contexts() # {context_id: [addon_names]}
Closes#253
