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/frc971/shifter_hall_effect.h b/frc971/shifter_hall_effect.h
index 991386d..4a0197c 100644
--- a/frc971/shifter_hall_effect.h
+++ b/frc971/shifter_hall_effect.h
@@ -1,8 +1,7 @@
 #ifndef FRC971_SHIFTER_HALL_EFFECT_H_
 #define FRC971_SHIFTER_HALL_EFFECT_H_
 
-namespace frc971 {
-namespace constants {
+namespace frc971::constants {
 
 // Contains the constants for mapping the analog voltages that the shifter
 // sensors return to the shifter position.  The code which uses this is trying
@@ -28,7 +27,6 @@
   double high_gear_middle;
 };
 
-}  // namespace constants
-}  // namespace frc971
+}  // namespace frc971::constants
 
 #endif