bctest.py is only used as an import by bitcoin-util-test.py. There's no
value in keeping it as a separate module, so let's merge them into a
single module to keep building and packaging simpler.
bitcoin-test-util is importable as a module, so if any future modules
really want to import the code from bctest.py, they can import
bitcoin-test-util and call the bctest functions by name.
Use shared config file for functional and util tests
The functional tests and util tests both require a config file that is
generated by ./configure. This commit merges those two config
files into a single configuration file that can be shared by both tests.
The config from config.ini is put into a Namespace object to maintain
the interface with bctest.py. A future commit could change this
interface to use a dictionary instead of a namespace.