Add targets for the turret aiming to shoot at

This adds a basic aiming algorithm that aims at the 3-point shot when we
think it can make it, and a 2-point shot otherwise.

Note: This also formalizes the fact that we are using the origin that is
defined by sift.fbs this year.

Change-Id: I04de0d01e2596bfa75226c6ac00af1d1d08d487f
diff --git a/frc971/control_loops/pose.h b/frc971/control_loops/pose.h
index 6b6628d..ab8afd0 100644
--- a/frc971/control_loops/pose.h
+++ b/frc971/control_loops/pose.h
@@ -42,6 +42,8 @@
 // position of (10, -5, 0) and a yaw of pi / 2, that suggests the robot is
 // facing straight to the left from the driver's perspective and is placed 10m
 // from the driver's station wall and 5m to the right of the center of the wall.
+// For 2020, we move the origin to be the center of the field and make positive
+// x always point towards the red alliance driver stations.
 //
 // Furthermore, Poses can be chained such that a Pose can be placed relative to
 // another Pose; the other Pose can dynamically update, thus allowing us to,