Kerberos 5 Credentials Cache Collection Utilities

This package is a rough rust port of the cccolutils python package.

The C part is inspired by the CPython extension from this python package, with some adaptations and fixes for all the memory leaks I could find (using valgrind with a small C test program, and the leak sanitizer from nightly rust for the rust code).

The available API is currently limited to the following functions:

• fn get_username_for_realm(realm: String) -> Result<Option<String>, String>: determine the username of the authenticated user for a given realm
• fn has_credentials() -> bool: determine if there are any active authentication tickets for any realm

The style of the C code is enforced with the uncrustify configuration in this directory.