fix lingering reference to "pytest" instead of "typ"
Add support for running inside a module hierarchy by default.

typ supports the ability to add a directory to sys.path with --top-level-dir,
but most of the time you can determine what the top level dir should be
if you are inside the tree, by looking upwards until you don't find an
__init__.py. This change does that automatically by default now.
Handle running with -c -j N slightly better.

Previously we would pop the -j from the command line, but not the
following argument, so coverage would get confused (we'd run
coverage typ -j 1 1) and we'd run no tests.