Remove unreachable code.

The removed case (pcHead == script.end()) can never be reached, since
we explicitly error out above if that is the case.  It is legacy from
Namecoin's merge-mining, which does not forbid this case earlier.
Merge pull request #748 from domob1812/fix-auxpow

Remove unreachable code.
Add %i to -blocknotify and replace it by the height of the block that the notification is about
Merge pull request #753 from langerhans/1.8.1-dev-blocknotify

Block height for blocknotify