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/y2019/joystick_angle.cc b/y2019/joystick_angle.cc
index 986a3fa..9baf9ed 100644
--- a/y2019/joystick_angle.cc
+++ b/y2019/joystick_angle.cc
@@ -4,9 +4,7 @@
 
 #include "frc971/zeroing/wrap.h"
 
-namespace y2019 {
-namespace input {
-namespace joysticks {
+namespace y2019::input::joysticks {
 
 using ::frc971::zeroing::Wrap;
 
@@ -47,6 +45,4 @@
 
   return JoystickAngle::kDefault;
 }
-}  // namespace joysticks
-}  // namespace input
-}  // namespace y2019
+}  // namespace y2019::input::joysticks