[WCM] var-dumper component

| Q             | A
| ------------- | ---
| Doc fix?      | no
| New docs?     | yes
| Applies to    | 2.6
| Fixed tickets | none

- [x] general introduction
- [x] cloner doc
- [x] caster doc
- [ ] dumper doc
- [ ] example output
- [ ] enhance the RST (with others, I'm far from a specialist)
I think the whole introduction is too long. In the other components, we usually have one introductional sentence which is rendered as a block quote. What about indenting onl the first sentence and start with "Built on top" at the first character of the next paragraph (which then might have to be reworded a bit)?