Real-time Update for Signatures

[rosenbrockc]

While fixing the real-time update for the docstrings, I changed the elements.Module.get_element() to use the start attribute instead of the absstart attribute that includes the docstrings of the code elements. This made it nice for docstrings since they were owned by the parent module and the module was found as owner for those edits; but now the signature update for rtupdate does not work. My guess is that get_element() is choosing the module as owner because start only marks the start of the body of the code element.

Probably we need to change get_element() back to how it was and then use the parent attribute of the code elements to get hold of the module for real-time docstring parsing.

[rosenbrockc]

I added an additional attribute to the Operation class in rtupdate.py that returned the docelement for the operation by taking the docstart and docend attributes into account for decorating documentation strings.