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/y2016/control_loops/superstructure/superstructure_controls.cc b/y2016/control_loops/superstructure/superstructure_controls.cc
index ee2020e..32c8b17 100644
--- a/y2016/control_loops/superstructure/superstructure_controls.cc
+++ b/y2016/control_loops/superstructure/superstructure_controls.cc
@@ -5,9 +5,7 @@
 #include "y2016/control_loops/superstructure/integral_arm_plant.h"
 #include "y2016/control_loops/superstructure/integral_intake_plant.h"
 
-namespace y2016 {
-namespace control_loops {
-namespace superstructure {
+namespace y2016::control_loops::superstructure {
 
 using ::frc971::PotAndIndexPosition;
 
@@ -254,6 +252,4 @@
   }
 }
 
-}  // namespace superstructure
-}  // namespace control_loops
-}  // namespace y2016
+}  // namespace y2016::control_loops::superstructure