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/buffered_pcm.cc b/frc971/wpilib/buffered_pcm.cc
index f356722..c64bbdc 100644
--- a/frc971/wpilib/buffered_pcm.cc
+++ b/frc971/wpilib/buffered_pcm.cc
@@ -7,8 +7,7 @@
 #include "hal/HAL.h"
 #include "hal/Ports.h"
 
-namespace frc971 {
-namespace wpilib {
+namespace frc971::wpilib {
 
 BufferedPcm::BufferedPcm(int module) : module_(module) {
   for (int i = 0; i < 8; ++i) {
@@ -53,5 +52,4 @@
   }
 }
 
-}  // namespace wpilib
-}  // namespace frc971
+}  // namespace frc971::wpilib