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/control_loops/drivetrain/spline_test.cc b/frc971/control_loops/drivetrain/spline_test.cc
index 6498fb6..6d84d53 100644
--- a/frc971/control_loops/drivetrain/spline_test.cc
+++ b/frc971/control_loops/drivetrain/spline_test.cc
@@ -9,10 +9,7 @@
 
 DEFINE_bool(plot, false, "If true, plot");
 
-namespace frc971 {
-namespace control_loops {
-namespace drivetrain {
-namespace testing {
+namespace frc971::control_loops::drivetrain::testing {
 
 std::string TestName() {
   const ::testing::TestInfo *info =
@@ -258,7 +255,4 @@
   }
 }
 
-}  // namespace testing
-}  // namespace drivetrain
-}  // namespace control_loops
-}  // namespace frc971
+}  // namespace frc971::control_loops::drivetrain::testing