lyra2: small changes and code cleanup
Enhance stale work detection + throughput fixes

seems to resolve solo mining lock on share.
export also computed solo work diff in api (not perfect)

In high rate algos, throughput should be unsigned...
This fixes keccak, blake and doom problems

And change terminal color of debug lines, to be selectable in putty,
color code is not supported in windows but selection is ok there.
solo: get bloc height and trap more errors

and disable multiple nonce on wallets,
a bloc cant be resolved twice ;)

Signed-off-by: Tanguy Pruvot <tanguy.pruvot@gmail.com>