Demo version 1.21d: Hotfix to level load crash + glitched backgrounds

Today I got alerted to an unavoidable crash in an older level that I hadn't test played in a while (whoops), so I rushed out this 1.21 hotfix to fix it. There's also some other misc bugfixes and balance changes included.

Full changelog:

• Fixed unavoidable 'unknown color' crash when entering Waste of Space.
• Fixed various glitches related to background rendering (Jupiter background in Waste of Space blocking all other graphics, seascape background in various Lake Slushi areas "leaking out" into other graphics, stage entrance background being cropped backwards during Burger Flip)
• Unlocking the slide ability does not make the dodgeroll from Dark Soul accessory unusable.
• Changed collision logic to use a 1 pixel bigger mask when colliding against objects compared to tiles, hopefully fixing misalignment that e.g. let you stand on 1-pixel ledges next to boss doors, seams between tiles and invisible walls, etc.
• Fixed clipping through a narrow slope in Pyramid Power during Burger Flip.
• Fixed Electroslime lightning not being upside-down during Burger Flip.
• Retro crocodile footsoldiers have a different dark-teal palette to contrast better against bushes and grass.
• Removed that one random bubble pipe hazard from the cybernetics lab entrance, it just added RNG for no reason.