Vidimera

Support Python 3.12/3.13 by separating tests for Python version 3.9-3.12 and 3.13+ due to changed Python behaviours.

Pass along scope to signature from other methods and functions

The following methods and functions now optionally accept a scope that is sent to behaviour.signature.

* `assert_implements`
* `behaviour.implements`
* `behaviour.implemented_by`

Introduces the concept of `MissingBehaviour` and adds a test helper in the form of `assert_implements`.

First alpha release.