Directories and Namespaces

Namespaces roughly correspond to directories, and classes to files, but not exactly.

• CASC/ implements special routines for CASC.
• Debug/ provides debugging utilities like assertions and tracebacks.
• Test/ contains various utilities for unit testing, as well as the main functions to integrate UnitTests/ with ctest.
• UnitTests/ contains the actual unit tests.
• TODO something about each directory please (even if just "unused")