Match dash or underscores

If the project name includes an `_`, all filenames and modules will also follow the same
naming convention. If the project name does not include an `_` or does include a `-`, all
filenames and modules will follow the same naming convention.

This is lisp, you really should be using dashes. :D

(I verified that it generates the files correctly and the 1st test run fails at the appropriate place.)