templates: avoid hex conversions internally

src/templates/witnesscommitment/output.js

@@ -1,26 +1,27 @@
-// OP_RETURN 36bytes:[0xaa21a9ed, Hash256(witnessRoot )]
+// OP_RETURN {aa21a9ed} {commitment}
 
 var bscript = require('../../script')
 var types = require('../../types')
 var typeforce = require('typeforce')
 var OPS = require('bitcoin-ops')
 
+var HEADER = new Buffer('aa21a9ed', 'hex')
+
 function check (script) {
   var buffer = bscript.compile(script)
 
   return buffer.length > 37 &&
     buffer[0] === OPS.OP_RETURN &&
     buffer[1] === 0x24 &&
-    buffer.slice(2, 6).toString('hex') === 'aa21a9ed'
+    buffer.slice(2, 6).equals(HEADER)
 }
 
 check.toJSON = function () { return 'Witness commitment output' }
 
 function encode (commitment) {
-  // hash256 0x21 hash160 0xed
   typeforce(types.Hash256bit, commitment)
 
-  return bscript.compile([OPS.OP_RETURN, new Buffer('aa21a9ed' + commitment.toString('hex'), 'hex')])
+  return bscript.compile([OPS.OP_RETURN, Buffer.concat([HEADER, commitment])])
 }
 
 function decode (buffer) {