Add python code to plot a x,y drivetrain spline

This gives us a path (and the various derivitives needed) to follow.
Next step is to start working out a velocity plan to follow the path.

Change-Id: Ic14425b98e8d51a4529b8df4d9351250067bb2bc
diff --git a/frc971/control_loops/python/BUILD b/frc971/control_loops/python/BUILD
index fb3e971..09945ba 100644
--- a/frc971/control_loops/python/BUILD
+++ b/frc971/control_loops/python/BUILD
@@ -96,3 +96,18 @@
     visibility = ["//visibility:public"],
     deps = ["//frc971/control_loops:python_init"],
 )
+
+py_binary(
+    name = "spline",
+    srcs = [
+        "spline.py",
+    ],
+    legacy_create_init = False,
+    restricted_to = ["//tools:k8"],
+    deps = [
+        "//external:python-gflags",
+        "//external:python-glog",
+        "//frc971/control_loops/python:controls",
+        "@matplotlib",
+    ],
+)