bitcoin/bitcoin — pull request #3076 by lano1106 (2013-10-10 16:45:32+00:00)
Title:  Make util phexdigit array reusable

class template base_uint had its own private lookup table.
This is saving 256 bytes per instantiation.

The result is not spectacular as bitcoin-qt has only shrinked of
about 1Kb but it is still valid improvement.

Also, I have replaced a for loop with a memset() call.

A unit_test has been added to check the change.

Signed-off-by: Olivier Langlois