const/high16 opcode had wrong implementation

IMHO the value of the opcode must be shifted by 16bits because const/high16 puts the 2bytes of data into the high part of the 32bit register.
this should fix issue 136 on google issue tracker: https://code.google.com/p/androguard/issues/detail?id=136

unfortunately this fixes it only for DAD and not for the bytecode format.