Need to wait until the internal fan out threads have been launched and acquired the testable mode lock before continuing with app starting and testing to avoid race conditions.

wip: fix propagation of initial values from control system variables (persistence layer) and device registers (just the current value)

This is needed to add all device variables to e.g. the history module.

TestableMode: ApplicationModule guarantees that the main loop thread had the testableModeLock at least once. Solves #66

  (first part of #65)

size_t has different types on 32 vs 64 bit systems. UL is correct for
64. Just use the ::size_type define to help it figure it out properly

- Exception handling decorator and ThreadedFanOut send condition variable notificatios via the DeviceModule
- FanOut sends terminate to impl and all slaves.
Solves (some?) shutdown issues, but breaks bi-directional array test.

supposedly fixed implementation, but tests are conceptually broken and/or implementation cannot be terminated

first implementation of device initialisation handler. Simple test passes, but needs to be extended.

implemented first interface change in DeviceModule to support initialisationHandlers. Test in place but failing due to missing implementation.

Fixes #39

added missing implementations of writeDestructively() - the inherited ones from the DeviceAccess classes are not doing the right thing...

rename VersionNumberUpdatingRegisterDecorator into MetaDataPropagatingRegisterDecorator, as it does more than just updating the VersionNumber now

So that the compiler complains if one accidentally uses it through
implicit type conversion "" -> bool and the hierarchy is screwed up

moved exception handling documentation into its own dox file and added documentation about DataValidity flag propagation