add error on EXTCODECOPY native contract and fix One256 push
add error on EXTCODECOPY native contract and fix One256 push

benjaminbollen/eris-db,silasdavis/burrow,benjaminbollen/eris-db,benjaminbollen/burrow,benjaminbollen/burrow,eris-ltd/eris-db,eris-ltd/eris-db,silasdavis/burrow,silasdavis/burrow