Cmake treats CMAKE_BUILD_TYPE string as case insensitve. Make the check
for enabling coverage reflect this to make usage less restrictive.

Do not try to make consuming control system variables bidirectional. It was running into an assertion and anyway makes no sense.

fix issue that a double "-l" can appear in the Makefile config shell scripts for libraries which already contain the -l

do not create TestableModeAccessorDecorator for unidirectional PVs with both directions enabled (was hitting an assert)

- treat the two directions of bidirectional variables properly in testable mode (i.e. as individual variables with each one counter)
- fix a data race in testable mode in case a bidirectional variable rejected a value (was not holding a required lock)

fixed bidirectional direct application to control system connections (without any FanOut in between)

extend test of bidirectional variables to include plain direct Application to ControlSystem connections (no FanOut etc. involved)

Fixed getCurrentVersionNumber() and setCurrentVersionNumber() so they always get/set the version number of the ApplicationModule and not e.g. of a VariableGroup.

extended the test to make sure also the "observer" variables in the control system show the right values

- implement ThreadedFanOut version with return channel
- add test for ThreadedFanOut with return channel

bidirectional variables: pass on version numbers in modules from the last blocking read on to any write operations, to resolve conflicts of concurrent variable updates properly

fixed testable mode for bidirectional variables: the return channel of control system to application variables must not increment the testableMode_counter

Implemented bidirectional process variables for control system variables. There are still bugs and the test is failing...

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.