fixed MVM_string_compare to return MVMint16 instead of MVMint64 *
Merge pull request #9 from zhuomingliang/patch-1

fixed MVM_string_compare to return MVMint16 instead of MVMint64 *
Remove duplicate, out-dated op list.
Map some I/O related ops.
Merge branch 'master' of https://github.com/MoarVM/MoarVM into zhuomingliang/patch-2
swtich radix op back to use int64 since int16 is NYI