Corrects asumptions about return values from HAL i2c

Also removes Broadcast, since it's never been implemented. It was
disabled from Java and  C++ before the season.

Author: ThadHouse

WPILib/I2C.cs

@@ -63,11 +63,10 @@ public bool Transaction(byte[] dataToSend, int sendSize, byte[] dataRecieved, in
                     Array.Copy(dataToSend, sendBuffer, Math.Min(sendSize, dataToSend.Length));
                 }
                 byte[] receiveBuffer = new byte[receiveSize];
-                bool aborted = true;
-                aborted = HAL_TransactionI2C((byte)m_port, (byte)m_deviceAddress, sendBuffer, (byte)sendSize, receiveBuffer, (byte)receiveSize) != 0;
+                int status = HAL_TransactionI2C((byte)m_port, (byte)m_deviceAddress, sendBuffer, (byte)sendSize, receiveBuffer, (byte)receiveSize);
                 if (receiveSize > 0 && dataRecieved != null)
                     Array.Copy(receiveBuffer, dataRecieved, Math.Min(receiveSize, dataRecieved.Length));
-                return aborted;
+                return status < 0;
             }
         }
 
@@ -158,19 +157,6 @@ public bool ReadOnly(byte[] buffer, int count)
             return retVal < 0;
         }
 
-        /// <summary>
-        /// Sends a broadcast write to all devices on the I2C bus.
-        /// </summary>
-        /// <remarks>This is currently not implemented.</remarks>
-        /// <param name="registerAddress">The register to write on all devices on the bus.</param>
-        /// <param name="data">The value to write to the devices.</param>
-        /// /// <returns>True if transfer was aborted, otherwise false.</returns>
-        public bool Broadcast(int registerAddress, int data)
-        {
-            //NOTE: Is also not implemented in the Java implementation of WPILib
-            throw new NotImplementedException();
-        }
-
         /// <summary>
         /// Verify that a device's registers contain expected values.
         /// </summary>