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/y2021_bot3/control_loops/superstructure/superstructure.cc b/y2021_bot3/control_loops/superstructure/superstructure.cc
index 1b4b611..16fa3d0 100644
--- a/y2021_bot3/control_loops/superstructure/superstructure.cc
+++ b/y2021_bot3/control_loops/superstructure/superstructure.cc
@@ -2,9 +2,7 @@
 
 #include "aos/events/event_loop.h"
 
-namespace y2021_bot3 {
-namespace control_loops {
-namespace superstructure {
+namespace y2021_bot3::control_loops::superstructure {
 
 using frc971::control_loops::AbsoluteEncoderProfiledJointStatus;
 using frc971::control_loops::PotAndAbsoluteEncoderProfiledJointStatus;
@@ -50,6 +48,4 @@
   (void)status->Send(status_builder.Finish());
 }
 
-}  // namespace superstructure
-}  // namespace control_loops
-}  // namespace y2021_bot3
+}  // namespace y2021_bot3::control_loops::superstructure