Made sample_ref a distinct (opaque) type in C

compiler/2014/C_CodeGen.jrag

examples/user_types/example_decoder.c

lib/c/2014/labcomm2014.h

lib/c/2014/labcomm2014_decoder.c

lib/c/2014/labcomm2014_encoder.c

lib/c/2014/labcomm2014_private.h

lib/c/2014/labcomm2014_renaming_decoder.c

lib/c/2014/labcomm2014_renaming_encoder.c

lib/c/2014/labcomm2014_type_signature.h

lib/c/2014/test/test_labcomm_copy.c

lib/c/2014/test/test_labcomm_generated_encoding.c

lib/c/2014/test/test_labcomm_renaming_decoder.c