halibot: define new top-level function to load HalObjects
halibot: define new top-level function to load HalObjects

This patch adds a new function, .load_object() that takes in a package/class
descriptor and loads the object from the package. This is the same loading
logic that was previously in the "private" ._instantiate_objects() function,
but now in a more publicly useful function.

Halibot/halibot,Halibot/halibot