Make it easier to have a lot of libraries

[virtuald]

CTRE in particular has a lot of libraries, and right now each one needs its own subpackage. Would be nice if we could just put everything in a single directory. Lots of changes needed to make this doable however.

FWIW, numpy is now doing this sort of thing:

       ``site-packages/numpy.libs/`` (linux), or
       ``site-packages/numpy/.dylibs/`` (macOS), or
       ``site-packages/numpy/.libs/`` (windows).