add memory safety to host contract revision
add memory safety to host contract revision

MrStrong/Sia,NebulousLabs/Sia,mtlynch/Sia,mharkus/Sia,mtlynch/Sia,NebulousLabs/Sia,mharkus/Sia,ChrisSchinnerl/Sia,MrStrong/Sia,ChrisSchinnerl/Sia,ericflo/Sia,ericflo/Sia