KGB 5.0 introduced new assertion methods in SpyAgency, which only

worked if mixing into a TestCase. This change improves upon this by

making these work even for a standalone SpyAgency, causing them to

just raise a standard AssertionError.
While consumers are unlikely to call these methods when not mixed into a

TestCase, an upcoming change will make use of these for some

sanity-checks.
There are also fixes for showing kwargs. Keys are now converted to

native strings, and are sorted. This helps with some unit test

discrepencies.

Unit tests passed.
Made use of this capability in an in-development change.