Fixes and Multiple Backgrounds in v4.1.1

v4.1.1 brings a set of main menu backgrounds from Arknights that change every time the player does things in the main menu! You will be able to see these after clearing the latest (somewhat hidden) episode.

Also are some changes and fixes such as the episode select screen being available after episode 1 because it gets mentioned on episode 2, and episode 4 is unlocked after episode 2 because episode 3 has a button that returns to the main menu which only gets clicked presumably because the player wants to skip to episode 4. When you update the game after a year you miss these things.

Something simple sounding as doing changing backgrounds on the main menu ended up being so convoluted and should not have taken as long as it did. By no revelation of my own I made it work thanks to these two posts

https://www.reddit.com/r/RenPy/comments/fwi7yt/random_main_menu_bg/

and

https://lemmasoft.renai.us/forums/viewtopic.php?p=547949

where I used a combination of these approaches to finally make it work.

I had actually stumbled on that second post quite early on, but I initially had no idea what they were talking about, and set off on my own trying to make multiple changing main menu backgrounds. After trying to do this unsuccessfully I learnt the hard way and came to realize I was having the exact same problem as the person asking the question on that post, at which point I tried using the same structure as they did in the post and it worked out in the end.

Renpy was pretty misleading on this one... As I was trying to change the value of the variable 'gui.main_menu_background' when you can simply go to screens.rpy and under the main menu screen have:
add "gui/main_menu.png"
using the path and filename of the background image directly instead of:
add gui.game_menu_background
(the variable) who is a middleman that you dont need. What a waste of time...