Measure text.

src/core.c

@@ -301,6 +301,17 @@ int lcoreSetWindowTitle( lua_State *L ) {
 	return 1;
 }
 
+/*
+> RL_lcoreCloseWindow()
+
+Close window and unload OpenGL context and free all resources
+*/
+int lcoreCloseWindow( lua_State *L ) {
+	state->run = false;
+
+	return 0;
+}
+
 /*
 ## Core - Timing
 */