permission protocol + reduce circular dependencies

lib/decoding.js

@@ -148,6 +148,21 @@ export const readVarUint = decoder => {
   }
 }
 
+/**
+ * Look ahead and read varUint without incrementing position
+ *
+ * @function
+ * @param {Decoder} decoder
+ * @return {number}
+ */
+export const peekVarUint = decoder => {
+  let pos = decoder.pos
+  let s = readVarUint(decoder)
+  decoder.pos = pos
+  return s
+}
+
+
 /**
  * Read string of variable length
  * * varUint is used to store the length of the string
@@ -189,3 +204,4 @@ export const peekVarString = decoder => {
   decoder.pos = pos
   return s
 }
+