Doxyfile: predefine DOXYGEN macro for preprocessing stage
FifoQueue: add FifoQueue::emplaceInternal()
FifoQueue: add FifoQueue::emplace()
FifoQueue: add FifoQueue::tryEmplace()
FifoQueue: add FifoQueue::tryEmplaceFor()
FifoQueue: add FifoQueue::tryEmplaceUntil()
FifoQueue: add template variant of FifoQueue::tryEmplaceFor()
FifoQueue: add template variant of FifoQueue::tryEmplaceUntil()
test: add type alias for type of "value" in OperationCountingType
test: extend FifoQueueOperationsTestCase with testing of
FifoQueue::*emplace*() functions