* spec tests: Data validity propagation
* update documentation links spec <-> tests

Co-authored-by: Dietrich Rothe <dietrich.rothe@desy.de>

Implement systematic tests for exception handling along specification.

This fixes redmin issues #8374, #8520 and #8364.

The previous order was causing actual race conditions, see #173.

	firt test D9 b for ThreadedFanOut

	Write tests for initial value initial value specification D.8

data validity propagation spec: Removed DataValidityCounter object, which simplifies the spec and the implementation.

- Reworked header.

- Reworked header.

- Reworked Header.
- Revised variable name. version -> versionBeforeRuntimeError

- Reworked header.

- Comment to B.2.5 explains that readability and writeability can change
- C.2.1.2 has more details about writeOrder

  - Added requirement that receivers are faulty on construction (1.8)
  - Clarified that validity can be set by the user code in 2.1.5

wip ExceptionHandlingSpec: C.2 ExceptionHandlingDecorator is throwing to implement skipping a transfer

* Added B.1.3 and B.1.4 : boost::numeric::bad_numeric_cast and boost::thread_interrupted are not treated
* Removed B.6 (behaviour for bad_numeric_cast)
* Removed C.2.8 (implementation for bad_numeric_cast)
* Re-numbered C.2.9 to C.2.8. It is the last section in C.2 and did not contain any anchors, so no references need to be changed.