DPL-nnn Remove n3 code

[JamesGlover]

Describe the Housekeeping
There is a large amount of code, and a few dependencies, to support 'Notation 3' (and inferences based on it. However, this isn't used in practice and can be removed.

Blocking issues
Describe any other issues or tickets that may be blocking this change.

Additional context
Add any other context about the problem here.