Helper getters for active transcoder set

Author: yondonfu

contracts/bonding/BondingManager.sol

@@ -783,6 +783,23 @@ contract BondingManager is ManagerProxyTarget, IBondingManager {
         return totalBonded;
     }
 
+    /*
+     * @dev Return total active stake for a round
+     * @param _round Round number
+     */
+    function getTotalActiveStake(uint256 _round) public view returns (uint256) {
+        return activeTranscoderSet[_round].totalStake;
+    }
+
+    /*
+     * @dev Return whether a transcoder was active during a round
+     * @param _transcoder Transcoder address
+     * @param _round Round number
+     */
+    function isActiveTranscoder(address _transcoder, uint256 _round) public view returns (bool) {
+        return activeTranscoderSet[_round].isActive[_transcoder];
+    }
+
     /*
      * @dev Update a transcoder with rewards
      * @param _transcoder Address of transcoder