fill checkmultisig scripts with 0s if not enough keys are available. add format function.

lib/bcoin/script.js

@@ -720,6 +720,9 @@ script.multisig = function(keys, m, n) {
   assert(m >= 1 && m <= n);
   assert(n >= 1 && n <= 15);
 
+  while (keys.length < n)
+    keys.push([]);
+
   // Keys need to be in a predictable order.
   keys = keys.sort(function(a, b) {
     return new bn(a).cmp(new bn(b)) > 0;
@@ -931,3 +934,37 @@ script.isValidSig = function(sig) {
 
   return true;
 };
+
+script.format = function(input, output) {
+  var scripts = [];
+
+  if (input) {
+    var script = input.script;
+    scripts.push(script);
+    if (input.out.tx && input.out.tx.outputs[input.out.index]) {
+      var prev = input.out.tx.outputs[input.out.index].script;
+      scripts.push(prev);
+      if (script.isScripthash(prev)) {
+        var redeem = script.decode(input.script[input.script.length - 1]);
+        scripts.push(redeem);
+      }
+    }
+  } else if (output) {
+    scripts.push(output);
+  }
+
+  scripts = scripts.map(function(script) {
+    return script.map(function(chunk) {
+      if (Array.isArray(chunk)) {
+        if (chunk.length === 0)
+          return 0 + '';
+        return utils.toHex(chunk);
+      }
+      if (typeof chunk === 'number')
+        return chunk + '';
+      return chunk;
+    }).join(' ');
+  });
+
+  return scripts;
+};