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/codelab/basic.cc b/frc971/codelab/basic.cc
index 66f08f9..a78da41 100644
--- a/frc971/codelab/basic.cc
+++ b/frc971/codelab/basic.cc
@@ -1,7 +1,6 @@
 #include "frc971/codelab/basic.h"
 
-namespace frc971 {
-namespace codelab {
+namespace frc971::codelab {
 
 Basic::Basic(::aos::EventLoop *event_loop, const ::std::string &name)
     : frc971::controls::ControlLoop<Goal, Position, Status, Output>(event_loop,
@@ -45,5 +44,4 @@
   }
 }
 
-}  // namespace codelab
-}  // namespace frc971
+}  // namespace frc971::codelab