This was causing a return value != 0 even when all interfields were
valid.

- `auxiliary-info` is specified as an optional field.

- `lvcnrcheck` gives a return code of `0` if the only failing fields are
  option and missing.

  However if fields are present and fail for other reasons (for example
  wrong type such as `str` when it should be `int`) then the return code
  will be `1`.

Falling back to format level 1 if the field is missing in the file to be
checked.

The `Spec` class family were originally set up to work using class
methods. This was natural because each `Spec` derivative only
represented a single field.

With the addition of the `Amplm` and `Phaselm` specs, this was no longer
true, with each of these specs required to represent a collection of
fields. While initially attempted to use instances for these `Specs` and
classes+classmethods for the remaining specs, to much off the logic
required casing on the `Spec` being an instance of class, it was decided
to only use classes and classmethods.

In the end this resulting in a massive anti-pattern, defining a class
factory in place of instance initialisers in the `Amplm` and `Phaselm`
classes, and a general bad logic. It made sense to use classmethods
before, but in no longer did.

This commit refactors most classmethods as instance methods (with a
couple left as classmethods because theydo not reference the parent
object, and could infact be staic methods). While a couple of
expressions required additional `()` to instance `Specs`, overall the
logic has been greatly simplified and actually demonstrated that the
classmethod paradigm previously used had significantly little benifit.

- Specs have been added that represent phase and amplitude modes.
- 5 degrees with everyone order of phase and amp modes fields are now
  created by `createValidSim`
- `lvcnrcheck` looks for and validates phase and amp modes.

`Specs.valid` now return `Error` objects and the logic of generating
errors and associated messages have been refactor to their own dedicated
module.

Much error message logic has now been removed from `lvcnrcheck` with
only specific cases handled as nessesary, right now only a `Missing`
`Error` needs to be cased.