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/y2020/actors/auto_splines.cc b/y2020/actors/auto_splines.cc
index 3ad292d..28aa996 100644
--- a/y2020/actors/auto_splines.cc
+++ b/y2020/actors/auto_splines.cc
@@ -2,8 +2,7 @@
 
 #include "frc971/control_loops/control_loops_generated.h"
 
-namespace y2020 {
-namespace actors {
+namespace y2020::actors {
 
 constexpr double kFieldLength = 16.4592;
 constexpr double kFieldWidth = 8.2296;
@@ -186,5 +185,4 @@
   return multispline_builder.Finish();
 }
 
-}  // namespace actors
-}  // namespace y2020
+}  // namespace y2020::actors
diff --git a/y2020/actors/autonomous_actor.cc b/y2020/actors/autonomous_actor.cc
index 160d36a..13b7d69 100644
--- a/y2020/actors/autonomous_actor.cc
+++ b/y2020/actors/autonomous_actor.cc
@@ -16,8 +16,7 @@
 DEFINE_bool(just_shoot, false,
             "If true, run the autonomous that just shoots balls.");
 
-namespace y2020 {
-namespace actors {
+namespace y2020::actors {
 
 using ::aos::monotonic_clock;
 using ::frc971::ProfileParametersT;
@@ -462,5 +461,4 @@
   return WaitUntilAbsoluteBallsShot(Balls() + num_wanted);
 }
 
-}  // namespace actors
-}  // namespace y2020
+}  // namespace y2020::actors