Fixing minor stuff, refactoring

src/Environment.h

@@ -14,6 +14,8 @@ namespace ZL {
 
 class Environment {
 public:
+	static constexpr int CONST_DEFAULT_WIDTH = 1280;
+	static constexpr int CONST_DEFAULT_HEIGHT = 720;
     static int windowHeaderHeight;
     static int width;
     static int height;