Statically linked builds strip all unused objects from their sources. This would be the case for the converters since they are nowhere called explicitly. In order to fix that, we use the same pattern as with the pipeline registration: The CMake build scripts parse all headers for an explicit template instantiation of a ConversionFunctionRegistrar. All these headers are included from the generated gen_converterregistration.h file, which is itself included from imagerepresentationconverter.cpp and thus gets compiled into the final executable also on static linking.

refs #474
refs #553