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/unwrap_test.cc b/frc971/zeroing/unwrap_test.cc
index b71c8b6..0a185b1 100644
--- a/frc971/zeroing/unwrap_test.cc
+++ b/frc971/zeroing/unwrap_test.cc
@@ -2,9 +2,7 @@
 
 #include "frc971/zeroing/wrap.h"
 
-namespace frc971 {
-namespace zeroing {
-namespace testing {
+namespace frc971::zeroing::testing {
 
 TEST(SensorTest, UnwrapOnce) {
   // Test the sensor moving over the maximum range value and wrapping once
@@ -63,6 +61,4 @@
   EXPECT_EQ(sensor.Unwrap(0.2), 0.2);   // move = 1.0, wrap -1
 }
 
-}  // namespace testing
-}  // namespace zeroing
-}  // namespace frc971
+}  // namespace frc971::zeroing::testing