Modify brackets in various prompts

Modified the brackets for starting a new game, resetting the config and confirming a video mode.

Quake/gl_vidsdl.c

@@ -873,7 +873,7 @@ static void VID_Test (void)
 	VID_Restart ();
 
 	//pop up confirmation dialoge
-	if (!SCR_ModalMessage("Would you like to keep this\nvideo mode? (y/n)\n", 5.0f))
+	if (!SCR_ModalMessage("Would you like to keep this\nvideo mode? [y/n]\n", 5.0f))
 	{
 		//revert cvars and mode
 		Cvar_SetValueQuick (&vid_width, old_width);

Quake/menu.c

@@ -390,7 +390,7 @@ void M_SinglePlayer_Key (int key)
 		{
 		case 0:
 			if (sv.active)
-				if (!SCR_ModalMessage("Are you sure you want to\nstart a new game? (y/n)\n", 0.0f))
+				if (!SCR_ModalMessage("Are you sure you want to\nstart a new game? [y/n]\n", 0.0f))
 					break;
 			IN_Activate();
 			key_dest = key_game;
@@ -1288,7 +1288,7 @@ void M_Options_Key (int k)
 			break;
 		case OPT_DEFAULTS:
 			if (SCR_ModalMessage("This will reset all controls\n"
-					"and stored cvars. Continue? (y/n)\n", 15.0f))
+					"and stored cvars. Continue? [y/n]\n", 15.0f))
 			{
 				Cbuf_AddText ("resetcfg\n");
 				Cbuf_AddText ("exec default.cfg\n");