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/y2014_bot3/shifter_hall_effect.h b/y2014_bot3/shifter_hall_effect.h
index a4bdeb8..0a65360 100644
--- a/y2014_bot3/shifter_hall_effect.h
+++ b/y2014_bot3/shifter_hall_effect.h
@@ -1,8 +1,7 @@
 #ifndef BOT3_SHIFTER_HALL_EFFECT_H_
 #define BOT3_SHIFTER_HALL_EFFECT_H_
 
-namespace bot3 {
-namespace constants {
+namespace bot3::constants {
 
 // Contains the voltages for an analog hall effect sensor on a shifter.
 struct ShifterHallEffect {
@@ -13,7 +12,6 @@
   double clear_high, clear_low;
 };
 
-}  // namespace constants
-}  // namespace bot3
+}  // namespace bot3::constants
 
 #endif