add GPU support for cracking GNOME Keyring files
External mode now refuses to resume unless a restore() function is present.

Add External:DumbDumb, the simplest and fastest possible exhaustive search
(if it can be made simpler or faster, please submit a patch!), defaulting
to printable ASCII. This is mostly added to demo/test the above.
Merge branch 'bleeding-jumbo' into memdbg

* bleeding-jumbo:
  External mode now refuses to resume unless a restore() function is present.
  add GPU support for cracking GNOME Keyring files