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/coerce_goal_test.cc b/frc971/control_loops/coerce_goal_test.cc
index 95520db..dc69b70 100644
--- a/frc971/control_loops/coerce_goal_test.cc
+++ b/frc971/control_loops/coerce_goal_test.cc
@@ -6,8 +6,7 @@
 
 #include "frc971/control_loops/polytope.h"
 
-namespace frc971 {
-namespace control_loops {
+namespace frc971::control_loops {
 
 namespace {
 
@@ -213,5 +212,4 @@
   EXPECT_EQ(result(1, 0), 0);
 }
 
-}  // namespace control_loops
-}  // namespace frc971
+}  // namespace frc971::control_loops