This adds a system for picture-in-picture UI windows using
vis_contents. Essentially, it allows you to make UI windows that show an area of turfs. It also refactors how cameranet visibility works.
Currently, this is implemented on AIs. They gain two new UI buttons - "Enter Multicam Mode", and "Create Multicam". When they go into Multicam Mode, they see a background of animated binary numbers, and they are allowed to create an infinite amount of these picture in picture windows, which subsequently creates an AI Eye for each one. They are able to control each AI eye individually, by first clicking on the PIP window to select it as "active" and then using the normal arrow key controls. The PIP windows can be freely resized and moved around the area.
You can control everything inside these PIP windows EXACTLY the same as you can using a traditional AI Eye, as demonstrated below.
For admins, there is a config option to disable PIP entirely - simply set `var/multicam_allowed = TRUE` to FALSE if you wish to disable it from being used. (Please be reasonable.) <3
You can see an example of how this works here:

AI Multicam functionality.
Do note that if the lightbulb in the AI core is busted, the multicam room is dark(er) than it would be, but you can still see your camera windows just fine. (I'll probably fix this later.) It only affects the "matrix" backdrop, the PIP windows are still fine.
This has been runtime-tested with the latest `master` revision and produces 0 runtimes, and has no noticeable impact on server CPU usage.
Polarisport is here! Port of https://github.com/VOREStation/VOREStation/pull/7752
The body zone selector now indicates which body part you are about to select when hovered over, and the hover inventory indicator basically shows where you are trying to put an item, and then shows an item ghost in red or green, giving visual feedback as to if that item will go in the slot or not.
Gifs of this in action:

Body Selection parts.

Inventory Icon Overlays!
Credit goes to @ShadowLarkens for original port to Paradise and assistance with port.
Shuttle tiles, default floors are still "regular".
Lava, sand, water, grass, beach, mining turfs all have sounds playing now for each footstep. <3
A small balance note - water tiles slow you down by 4, and 8 for deep/ocean tiles. I'll remove these and put them in a separate PR if requested.
Massive credit to @Arokha for helping me figure out the floor system and sitting through getting it put together. <3 <3 <3
* Adds preference to control multilingual behaviour
Examine mode preference should persist across reconnections to a single round
Still looking into how to properly get these to go into the savefile
* typos