Made DMA compile again, and fixed analog bugs.

Change-Id: Ib4ff5fd48eddfc1e6f15b97fe6fda977258c96f7
diff --git a/frc971/wpilib/encoder_and_potentiometer.h b/frc971/wpilib/encoder_and_potentiometer.h
index 82fa9a8..2450841 100644
--- a/frc971/wpilib/encoder_and_potentiometer.h
+++ b/frc971/wpilib/encoder_and_potentiometer.h
@@ -141,7 +141,7 @@
     dma->Add(encoder_.get());
     dma->Add(index_.get());
     dma->Add(potentiometer_.get());
-    dma->SetExternalTrigger(index_.get(), true, false);
+    dma->SetExternalTrigger(index_.get(), true, true);
   }
 
  private: