remove silly rmultinom_sparse test
remove silly rmultinom_sparse test

writing a test that, if it is correctly written, fails with probability
0.05 is not useful. Unfortunately I don't have a smart way to test the
sanity of rmultinom_sparse. Somebody light the Stat Signal!

agoldst/dfrtopics,agoldst/dfrtopics,agoldst/dfrtopics,agoldst/dfrtopics,agoldst/dfrtopics