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/averager_test.cc b/frc971/zeroing/averager_test.cc
index 50eac72..d4f154a 100644
--- a/frc971/zeroing/averager_test.cc
+++ b/frc971/zeroing/averager_test.cc
@@ -2,8 +2,7 @@
 
 #include "gtest/gtest.h"
 
-namespace frc971 {
-namespace zeroing {
+namespace frc971::zeroing {
 
 class AveragerTest : public ::testing::Test {
  protected:
@@ -57,5 +56,4 @@
   ASSERT_EQ(0.0, averager.GetAverage()(0, 0));
 }
 
-}  // namespace zeroing
-}  // namespace frc971
+}  // namespace frc971::zeroing