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/shooter_interpolation/interpolation.cc b/frc971/shooter_interpolation/interpolation.cc
index 66b2cf9..1faa046 100644
--- a/frc971/shooter_interpolation/interpolation.cc
+++ b/frc971/shooter_interpolation/interpolation.cc
@@ -4,12 +4,10 @@
 #include <utility>
 #include <vector>
 
-namespace frc971 {
-namespace shooter_interpolation {
+namespace frc971::shooter_interpolation {
 
 double Blend(double coefficient, double a1, double a2) {
   return (1 - coefficient) * a1 + coefficient * a2;
 }
 
-}  // namespace shooter_interpolation
-}  // namespace frc971
+}  // namespace frc971::shooter_interpolation