Default to requiring frc namespace for wpilibc. (#972)

Instead of defining NAMESPACED_WPILIB to remove the "using namespace frc"
shim in Base.h, instead require NO_NAMESPACED_WPILIB be defined to add it.

Fix up various examples to use correct namespacing.

wpilibc/src/main/native/include/Base.h

@@ -52,6 +52,6 @@ struct HasBeenMoved {
 }  // namespace frc
 
 // For backwards compatibility
-#ifndef NAMESPACED_WPILIB
+#ifdef NO_NAMESPACED_WPILIB
 using namespace frc;  // NOLINT
 #endif