Ported the polydrivetrain code over to C++.
diff --git a/frc971/control_loops/update_polydrivetrain.sh b/frc971/control_loops/update_polydrivetrain.sh
new file mode 100755
index 0000000..71e5d09
--- /dev/null
+++ b/frc971/control_loops/update_polydrivetrain.sh
@@ -0,0 +1,6 @@
+#!/bin/bash
+#
+# Updates the drivetrain controller.
+
+./python/polydrivetrain.py drivetrain/polydrivetrain_motor_plant.h \
+    drivetrain/polydrivetrain_motor_plant.cc