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/wpilib_interface.cc b/y2019/wpilib_interface.cc
index b3a5953..16102f4 100644
--- a/y2019/wpilib_interface.cc
+++ b/y2019/wpilib_interface.cc
@@ -66,8 +66,7 @@
 namespace chrono = ::std::chrono;
 using std::make_unique;
 
-namespace y2019 {
-namespace wpilib {
+namespace y2019::wpilib {
 namespace {
 
 constexpr double kMaxBringupPower = 12.0;
@@ -821,7 +820,6 @@
 };
 
 }  // namespace
-}  // namespace wpilib
-}  // namespace y2019
+}  // namespace y2019::wpilib
 
 AOS_ROBOT_CLASS(::y2019::wpilib::WPILibRobot);