Underscore, not dash in module name (PEP8)

[projectweekend]

https://www.python.org/dev/peps/pep-0008/#package-and-module-names

The dash used in this file name causes a syntax error when attempting to import using the example code:

from ada-matrix import DriverAdaMatrix

After renaming the module ada_matrix.py and adjusting the example import, it works fine:

from ada_matrix import DriverAdaMatrix

[bbarrilleaux]

CC @PaintYourDragon

This PR fixes the Bibliopixel driver -- the hyphen isn't valid python. I've been happily using the Bibliopixel driver after making this correction in my own copy of the code.