[WIP] Example of Custom Element Wrapper

[EZoni]

This is a prototype of custom element wrapper that could be done to achieve what was discussed in #3 (review) and #3 (comment).

In YAML format, the custom element wrapper produces this format

kind: Line
line:
- Drift:
    length: 0.25
    name: drift1
- Quadrupole:
    MagneticMultipoleP:
      Bn1: 1.0
    length: 1.0
    name: quad1
- Drift:
    length: 0.5
    name: drift2
- Quadrupole:
    MagneticMultipoleP:
      Bn1: -1.0
    length: 1.0
    name: quad2
- Drift:
    length: 0.5
    name: drift3

instead of this format

kind: Line
line:
- kind: Drift
  length: 0.25
  name: drift1
- MagneticMultipoleP:
    Bn1: 1.0
  kind: Quadrupole
  length: 1.0
  name: quad1
- kind: Drift
  length: 0.5
  name: drift2
- MagneticMultipoleP:
    Bn1: -1.0
  kind: Quadrupole
  length: 1.0
  name: quad2
- kind: Drift
  length: 0.5
  name: drift3

This would be alternative to the custom read/write example in #8.

[EZoni]

Closing as obsolete.