Removed unused constant in DH3KDHPartOnePacket

The constant is unused and, if it was used, would be redundant with DHPartOnePacket.Type.

Most likely a leftover from copy-pasting the constructors, expecting it to be needed in the way it is in the super class constructor.
Merge pull request #98 from Strilanc/patch-4

Removed unused constant in DH3KDHPartOnePacket