Remove dead code from half

[cary-ilm]

• move eLut.h, imath_float_half_exp_table, and long_convert to
  ImathTest. They're useful to validate behavior in the test but have
  no use in the actual library.

Signed-off-by: Cary Phillips cary@ilm.com

[kdt3rd]

Thanks for cleaning things up - I was a bit chicken to change too much without being able to go back. Since you have the branch, could you also remove the definition of long_convert from half.h? I don't see that in the diffs.

[cary-ilm]

I don't see any reason to be hesitant, the changes are demonstrable improvements so better to fully commit to them and make the code as clear as possible. It's easy enough to recover the old code from past release branches. And the old code is still present in the test as well.

Actually, rather than making the performance test execute both new and old code, it might be simpler to write a single routine that measures performance and then patch it into the RB-3.0 branch. Then measure the difference with separate runs built against different branches. It would also provide an easier way of measuring future changes.