This commit merges the NodeConnCB and SingleNodeConnCB into a single
class (called NodeConnCB). The original intent for the NodeConnCB was to
be able to have a python 'mininode' connect to multiple running
bitcoinds. This has never been used and can be achieved more easily by
having multiple NodeConns backed by a common datastore if it is ever
needed.
The changes in mininode.py are just code moves (and merging the two
classes into a single class). The code changes in the individual test
cases are changing the subclasses to subclass from NodeConnCB instead of
SingleNodeConnCB. There is a lot of duplicate code in the subclasses
that can be removed in future commits.
assumevalid was merged as part of PR 9484, but was not added to the
test_runner, so is not run even as part of the extended tests.
This commit adds assumevalid to the list of tests in test_runner. It
also clarifies the code in assumevalid considerably.