Simpler "one step" name registration

This implements a proposed hardfork to enable a new and simpler method to register names in a single step - just by an `OP_NAME_FIRSTUPDATE` script without rand value and without preceding `OP_NAME_NEW`.  This removes the "name stealing" protection offered by `OP_NAME_NEW` in Namecoin, but this is probably no big deal for Huntercoin.

See also http://forum.huntercoin.org/index.php?topic=170.0.