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/y2020/control_loops/superstructure/superstructure.cc b/y2020/control_loops/superstructure/superstructure.cc
index b7d57b4..f951791 100644
--- a/y2020/control_loops/superstructure/superstructure.cc
+++ b/y2020/control_loops/superstructure/superstructure.cc
@@ -4,9 +4,7 @@
 #include "aos/events/event_loop.h"
 #include "aos/network/team_number.h"
 
-namespace y2020 {
-namespace control_loops {
-namespace superstructure {
+namespace y2020::control_loops::superstructure {
 
 using frc971::control_loops::AbsoluteAndAbsoluteEncoderProfiledJointStatus;
 using frc971::control_loops::AbsoluteEncoderProfiledJointStatus;
@@ -313,6 +311,4 @@
   }
 }
 
-}  // namespace superstructure
-}  // namespace control_loops
-}  // namespace y2020
+}  // namespace y2020::control_loops::superstructure