Plug in transformers

[rob-metalinkage]

Allow users to use their own code to extend the available transformers.

requires examples, documentation and tutorial.

[rob-metalinkage]

Following discussions - some further ideas.

Generalise transformers to a plug in, with ability to characterise types (so "transformers" button can be renamed, and have multiple buttons)

General model pre-process -> validate -> execute -> validate output -> visualise in viewer

execution could be:

• run a transform using a supported language
• execute a function

validation could be some of:

• syntax
• schema
• shacl
• expected result comparison

multiple transforms may occur - a key one is geometry-for-visualisation, or visualisation (e.g. 3D)

Validation could be extended to include service look-ups.

visualisation of examples is also pluggable.

Need to have the chained model, but be able to see the various artefacts in relation to each other

[avillar]

I consider this implemented.