Adding QAM16 to Benchmark_TX and RX

Hi,

I am wanting to use the available 16QAM modulation scheme to the
benchmark_tx/rx programs that come with GNU Radio.

What I have done so far is remove the comments from the bottom of the
qam16.py files to add them to the type one modulation, but when I run
benchmark the options for qam16 are still not available.

I am assuming there is another change in some code I have to do but I am
unsure where this is???

Cheers,

Michael