allow gpu-threads to be set on a per-card basis with ADL support

credit - SGMiner
update new routine for default TC to use gpu->threads

clean up some leftover debugging framework from 3.4.2
clean up routine for guessing TC/BS if not specified to take
--gpu-threads into account
don't show intensity in manage_gpu

it's already shown in the line above, as -X and -R are available.