Update Duplicator with changes from MC 1.7 (#31)

Added to keepData: 3, 12, 38, 95, 160, 161, 162, 175

Added protection to duplication of DOUBLE_PLANT. Bug in Minecraft 1.7.2
crashes the game when a DOUBLE_PLANT with data value 11 is in the
inventory. As duplicating the top half is pointless anyways, just
disabled it entirely. Click the bottom half of DOUBLE_PLANT to
duplicate.