Gudhi is following PEP8 conventions.

Please refer to:
https://www.python.org/dev/peps/pep-0008/

A summary:
 - modules (filenames) should have short, all-lowercase names, and they can contain underscores.
 - packages (directories) should have short, all-lowercase names, preferably without underscores.
 - classes should use the CapWords convention.