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/pot_and_index_test.cc b/frc971/zeroing/pot_and_index_test.cc
index f2e464f..ef90661 100644
--- a/frc971/zeroing/pot_and_index_test.cc
+++ b/frc971/zeroing/pot_and_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::PotAndIndexPulseZeroingConstants;
 
@@ -278,6 +276,4 @@
   ASSERT_TRUE(estimator.error());
 }
 
-}  // namespace testing
-}  // namespace zeroing
-}  // namespace frc971
+}  // namespace frc971::zeroing::testing