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/motors/usb/queue.cc b/motors/usb/queue.cc
index 270ad74..3d2e283 100644
--- a/motors/usb/queue.cc
+++ b/motors/usb/queue.cc
@@ -4,8 +4,7 @@
 
 #include <algorithm>
 
-namespace frc971 {
-namespace teensy {
+namespace frc971::teensy {
 
 size_t Queue::Read(char *out_data, size_t out_size) {
   const size_t read_cursor = read_cursor_.load(::std::memory_order_relaxed);
@@ -30,5 +29,4 @@
   return r;
 }
 
-}  // namespace teensy
-}  // namespace frc971
+}  // namespace frc971::teensy