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/zeroing/pulse_index_test.cc b/frc971/zeroing/pulse_index_test.cc
index bd257f7..c07644d 100644
--- a/frc971/zeroing/pulse_index_test.cc
+++ b/frc971/zeroing/pulse_index_test.cc
@@ -4,9 +4,7 @@
 
 #include "frc971/zeroing/zeroing_test.h"
 
-namespace frc971 {
-namespace zeroing {
-namespace testing {
+namespace frc971::zeroing::testing {
 
 using constants::EncoderPlusIndexZeroingConstants;
 
@@ -127,6 +125,4 @@
   }
 }
 
-}  // namespace testing
-}  // namespace zeroing
-}  // namespace frc971
+}  // namespace frc971::zeroing::testing