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_reader.cc b/y2019/joystick_reader.cc
index 12f590f..b44d084 100644
--- a/y2019/joystick_reader.cc
+++ b/y2019/joystick_reader.cc
@@ -41,9 +41,7 @@
 
 namespace chrono = ::std::chrono;
 
-namespace y2019 {
-namespace input {
-namespace joysticks {
+namespace y2019::input::joysticks {
 
 namespace superstructure = y2019::control_loops::superstructure;
 
@@ -669,9 +667,7 @@
       ::aos::monotonic_clock::time_point::min();
 };
 
-}  // namespace joysticks
-}  // namespace input
-}  // namespace y2019
+}  // namespace y2019::input::joysticks
 
 int main(int argc, char **argv) {
   ::aos::InitGoogle(&argc, &argv);