test for valid neuroml2

[borismarin]

No description provided.

[pgleeson]

Have added backends jNeuroML_validate and jNeuroML_validatev1 for this.

[borismarin]

Shouldn't we always validate nml for any jnml-based backend? Without the need for separated backeds? This way, it seems that we will be delegating functionality to backend names, and the number of different b-e will grow just to implement specific features.
If there's a nml target involved, I suggest trying to validate agains both schemata (v1,v2) and, if it fails for both, stop testing.

[borismarin]

It can maybe fit within #7

[pgleeson]

There can be some cases where an nml file is known to be not valid, e.g. included new elements, but jNeuroML still treats them as LEMS & jNeuroML successfully runs.

If a user wants to explicitly state that all nml files are valid they can easily add a test file like:
https://github.com/OpenSourceBrain/ACnet2/blob/master/neuroConstruct/generatedNeuroML2/.test.validate.omt