Remove RACK_FLATTEN_NAMESPACES since it is not known to be used.

include/rack.hpp

@@ -100,22 +100,19 @@
 namespace rack {
 
 
-/** Define this macro before including this header to prevent common namespaces from being included in the main `rack::` namespace. */
-#ifndef RACK_FLATTEN_NAMESPACES
-	// Import some namespaces for convenience
-	using namespace logger;
-	using namespace math;
-	using namespace widget;
-	using namespace ui;
-	using namespace app;
-	using plugin::Plugin;
-	using plugin::Model;
-	using namespace engine;
-	using namespace componentlibrary;
+// Import some namespaces for convenience
+using namespace logger;
+using namespace math;
+using namespace widget;
+using namespace ui;
+using namespace app;
+using plugin::Plugin;
+using plugin::Model;
+using namespace engine;
+using namespace componentlibrary;
 
-	// Import namespace recursively to solve the problem of calling `rack::DEBUG(...)` which expands to `rack::rack::logger(...)`.
-	namespace rack = rack;
-#endif
+// Import namespace recursively to solve the problem of calling `rack::DEBUG(...)` which expands to `rack::rack::logger(...)`.
+namespace rack = rack;
 
 
 } // namespace rack