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/y2019/control_loops/superstructure/superstructure.cc b/y2019/control_loops/superstructure/superstructure.cc
index e796f0b..8a38e7a 100644
--- a/y2019/control_loops/superstructure/superstructure.cc
+++ b/y2019/control_loops/superstructure/superstructure.cc
@@ -6,9 +6,7 @@
 #include "frc971/control_loops/static_zeroing_single_dof_profiled_subsystem.h"
 #include "y2019/status_light_generated.h"
 
-namespace y2019 {
-namespace control_loops {
-namespace superstructure {
+namespace y2019::control_loops::superstructure {
 
 using frc971::control_loops::AbsoluteEncoderProfiledJointStatus;
 using frc971::control_loops::PotAndAbsoluteEncoderProfiledJointStatus;
@@ -214,6 +212,4 @@
   }
 }
 
-}  // namespace superstructure
-}  // namespace control_loops
-}  // namespace y2019
+}  // namespace y2019::control_loops::superstructure