check for OP_RETURN in Script.isScriptHashIn()

- Data transactions consist of OP_RETURN followed by a push of bytes
  to the stack
- P2SH redeem scripts (generally) consist of signatures and relevant
  information followed by a push of bytes to the stack
- To differentiate the two, we check that the first OP code is not
  OP_RETURN in Script.isScriptHashIn()

lib/script/script.js

@@ -393,7 +393,7 @@ Script.prototype.isScriptHashOut = function() {
  * Note that these are frequently indistinguishable from pubkeyhashin
  */
 Script.prototype.isScriptHashIn = function() {
-  if (this.chunks.length <= 1) {
+  if (this.chunks.length <= 1 || this.chunks[0].opcodenum === Opcode.OP_RETURN) {
     return false;
   }
   var redeemChunk = this.chunks[this.chunks.length - 1];