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/dma_edge_counting.cc b/frc971/wpilib/dma_edge_counting.cc
index 4e8a158..c84bc15 100644
--- a/frc971/wpilib/dma_edge_counting.cc
+++ b/frc971/wpilib/dma_edge_counting.cc
@@ -2,8 +2,7 @@
 
 #include "aos/logging/logging.h"
 
-namespace frc971 {
-namespace wpilib {
+namespace frc971::wpilib {
 
 bool DMAEdgeCounter::ExtractValue(const DMASample &sample) const {
   return sample.Get(input_);
@@ -101,5 +100,4 @@
   }
 }
 
-}  // namespace wpilib
-}  // namespace frc971
+}  // namespace frc971::wpilib