Added memory arena

Fixed frames in flight validation error in vulkan
Added some utility macros
Added function decorator macros
Added some consolidation headers/code include files

code/core/core.h

@@ -0,0 +1,9 @@
+#if !defined(LD_CORE_CORE_H_)
+#define LD_CORE_CORE_H_
+
+#include "types.h"
+#include "platform.h"
+#include "macros.h"
+#include "arena.h"
+
+#endif  // LD_CORE_CORE_H_