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/wpilib/gyro_sender.cc b/frc971/wpilib/gyro_sender.cc
index ac88acb..934daf8 100644
--- a/frc971/wpilib/gyro_sender.cc
+++ b/frc971/wpilib/gyro_sender.cc
@@ -16,8 +16,7 @@
 #include "frc971/queues/gyro_uid_generated.h"
 #include "frc971/zeroing/averager.h"
 
-namespace frc971 {
-namespace wpilib {
+namespace frc971::wpilib {
 
 namespace chrono = ::std::chrono;
 using ::aos::monotonic_clock;
@@ -145,5 +144,4 @@
   }
 }
 
-}  // namespace wpilib
-}  // namespace frc971
+}  // namespace frc971::wpilib