In terminate(), call interrupt only when wait_for_new_data is set

- All accessors come up in exception state.
- Read-accessors increase counter in init phase

Assertion is gone, but tests still failing

  - Rewrite on exception counter change
  - getDataValidity respects exception and dataFault counters

  - EntityOwner has individual counters for both events
  - Adapted all instances of increment/decrementDataFaultCounter
  - Not changed getDataValidity() implementation yet
  - Tests failing

change declaration of 'decrementDataFaultCounter' in 'EntityOwner' to take a bool parameter and adjust rest of the code to it
implement 'decrementDataFaultCounter' in 'ApplicationModule' according to ticket #95 -> rewrite all outputs when 'faultCounter' goes from 1 to 0

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

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

move ApplicationModule::appConfig() to ModuleImpl::appConfig() so it can also be used from ModuleGroup

Implemented first part of #17: A HierarchyModifier can now be specified instead of the eliminateHierarchy boolean flag. No new functionality is yet added.

Added preliminary support for bidirectional variables. There are still some known issues, e.g. concurrent updates can still lead to race conditions. This will be addressed soon.

Unfortunatly this currently breaks the ServerHistory module, as it relies on slashes in accessor names. The MicroDAQ module had the same issue but has already been fixed. This fix can be adopted to the ServerHistory module as well.

removed incorrect implementation of operator[] and operator() in ApplicationModule (and use the implementations of ModuleImpl instead)

fixed connectTo() so it now uses the dynamic/virtual model and thus obeys e.g. eliminated hierarchies etc.

introduced a ModuleGroup (grouping ApplicationModules and other ModuleGroups) and enforced a proper hierarchy of modules to exclude that an ApplicationModule can own (directly or indirectly) another ApplicationModule

Renamed Application::testableModeThreadName() into Application::threadName(), since this will be used for other purposes as well.

Changed Module::connectTo() to accept also temporary module objects, e.g. as returned by findTag(). As a consequence, the operators [] and () of the modules had to be changed to const.