api: export card labels and count, renames stats command

renammed to "threads", stats was too much generic
nvml: attempt to use another clock function

But no way, even recent 346 driver series or 343. Seems limited to
Tesla products...
update readme for final 1.4.9

A dev version was released on http://cryptomining-blog.com/

Please update, the previous one has some bugs when using multiple
gpus and the API format has changed!