Nest all namespaces

The compiler supports this now.  We can type less going forward.
No functional changes.

Signed-off-by: Stephan Pleines <pleines.stephan@gmail.com>
Change-Id: I29d6fa4f9aacc0e381f1a7637294db0392466995
diff --git a/frc971/control_loops/quaternion_utils_test.cc b/frc971/control_loops/quaternion_utils_test.cc
index 32b1915..4e9e97a 100644
--- a/frc971/control_loops/quaternion_utils_test.cc
+++ b/frc971/control_loops/quaternion_utils_test.cc
@@ -10,9 +10,7 @@
 #include "frc971/control_loops/jacobian.h"
 #include "frc971/control_loops/runge_kutta.h"
 
-namespace frc971 {
-namespace controls {
-namespace testing {
+namespace frc971::controls::testing {
 
 // Tests that small perturbations around a couple quaternions averaged out
 // return the original quaternion.
@@ -212,6 +210,4 @@
   EXPECT_NEAR(0.0, (uz - integral3 * uz).norm(), 5e-2);
 }
 
-}  // namespace testing
-}  // namespace controls
-}  // namespace frc971
+}  // namespace frc971::controls::testing