Use a flags table for setMode now, implement resizable and borderless windows, and add resize event

Example setMode invocation: love.graphics.setMode(800, 600, {fullscreen = false, vsync = true, borderless = true})
t.screen.resizable and t.screen.borderless are available in love.conf
And love.resize(w, h) gets called if it exists on a resize event.
NOTE: love.handlers.resize(w, h) does the required setMode, but that does mean a visual reload

--HG--
branch : minor

src/modules/event/sdl/Event.cpp

@@ -142,6 +142,13 @@ Message *Event::convert(SDL_Event &e)
 	case SDL_QUIT:
 		msg = new Message("quit");
 		break;
+	case SDL_VIDEORESIZE:
+		arg1 = new Variant((double) e.resize.w);
+		arg2 = new Variant((double) e.resize.h);
+		msg = new Message("resize", arg1, arg2);
+		arg1->release();
+		arg2->release();
+		break;
 	}
 
 	return msg;