autodep8 support

It would be fantastic if we could auto-generate a smoke-test for externals.

• load each external
• try creating each object for which there is a help-patch
• try loading each help-patch

i guess abstractions should declare all dependencies (via [declare]), so creating an abstraction where any object fails to instantiate could be considered a bug.

we probably also want some way to blacklist objects from tests, e.g.

## debian/tests/autopkgtest-pkg-puredata.conf

# start Pd with these extra arguments
extra_pdargs: -lib Gem
# do not attempt to load these libraries
skip_pd_libraries: flub, flob
# do not attempt to instantiate these objects
skip_pd_objects: autocrash
# do not fail if any of these objects cannot be instantiated
allow_uncreatable: packOSC