[ci skip]

This is required for conversion to NEURON. The members themselves do not
need to be included.

The schema does not require the `name` attribute in `Segment`. However,
the NEURON code generator seems to require it:

```
Exception: java.lang.NullPointerException: Cannot invoke "String.equals(Object)" because the return value of "org.neuroml.model.Segment.getName()" is null
```

… `Exception`

Specific errors are better than generic ones.

This is required to ensure that segment groups have already been defined
before they are included in the default ones.

No need for it to be limited to the utility function.

…ising

otherwise sphinx fails with:

```
  File
  "/home/asinha/Documents/02_Code/00_mine/NeuroML/software/libNeuroML/neuroml/loaders.py",
  line 191, in <module>
      ) -> neuroml.nml.nml.NeuroMLDocument:
      AttributeError: module 'neuroml' has no attribute 'nml'

```

Not sure what the root cause is, but this tweak fixes it.

Feat/cell optimise natsort -> exp

Given that we have a well defined structure, we should ideally be able
to generate all paths automatically. The information is present, we just
need to figure out how to use it.

Towards semi-automated path generation

Use natsort to properly sort segments/groups when optimising

To v0.5.4

To v0.5.5; updated schema (with hindmarsh rose) and regenerated nml.py