stablerange: stop using '.node' in subrangesclosure We access the range-head revision number by index and convert it on site.

stablerange: have the class behave as a tuple If we want people to use a tuple, we should offer them a tuple. This should help update most of the code iteratively.

obshashrange: extract computation back into the discovery module This obshash is related to discovery and it seems more appropriate to have to live there. This remove the last large piece of logic from the class. We'll now be able to slowly turn it into a tuple.

obshashrange: use a small utility function to access the obshash If we want the object to disappear we needs the top level code to stop accessing its attribute.

debugstablerange: minor code reformat The content of that list will become more complex as we drop the object so we make sure to have one value per line for clarity.

stablerange: move the subrangesclosure inside the module This seems more suitable and open the way to simple update of how we build things without too much impact outside the module. The debug command is still in the 'obsdiscovery' module because it also deal to obshash and I'm not sure of were this should live yet.