Add Neg trait for base types (Z, Q)

[supinie]

Description

Implements the Neg trait for the 'base' types Z and Q

This PR implements...

• Neg for Z
• Neg for Q

Hope to follow implementation for all types shortly.

Testing

• I added basic working examples (possibly in doc-comment)
• I added tests for large (pointer representation) values
• I included tests for all reasonable edge cases

Checklist:

• I have performed a self-review of my own code
  • The code provides good readability and maintainability s.t. it fulfills best practices like talking code, modularity, ...
    • The chosen implementation is not more complex than it has to be
  • My code should work as intended and no side effects occur (e.g. memory leaks)
  • The doc comments fit our style guide
  • I have credited related sources if needed

[Marvin-Beckmann]

Looks good! Thanks for contributing! :)

[supinie]

Noticed a bad link in the docs, fixed now.