[TFTD] [CheatSuite] Aqua-Plastics Rework

TFTD Aqua-Plastics Rework for OpenXCom

** This is intended to be used with my TFTD CheatSuite - See https://openxcom.mod.io/cheat-suite

PLEASE discuss this on the OpenXCom forums @ https://openxcom.org/forum/index.php/topic,7630.msg120095.html
The Mod portal has no notification for comments, so I will not see them.

This makes a number of changes and introduces several plastics-integrated versions of Earth technology to the game. Plastic coelecanths, flying subs, and crude plastic-plated diving suits. This mod includes my research fix for the Gauss Coelecanth, which removes the nonsensical New-Flying-Sub prerequisite for it.

The intention is to make Aqua-Plastics discovery and research make a bit more sense, and be a bit more believable (at least for me). I find it absolutely incredulous that your best-and-brightest scientists, engineers and technicians discover this new wonder-material and do absolutely nothing with it until mid-late-game. I'm trying to avoid making large changes to the gameplay experience [And I have the artistic ability of a turnip], so little new artwork or battlescape units are planned.

This is tested on OpenXCom Extended, though to my knowledge it should work fine on vanilla OpenXCom.

Changes to vanilla:

* The economics of the Gauss Coelecanth required a tweak, making them less viable as a money-making item. Realistically this makes no difference as you're better off selling the big Gauss Cannon anyways.

* A tiny tweak to the Aqua-Plastics UFOPedia page is needed for any of this to make sense.

* Plastic Aqua Armor now requires dissection of either a Deep One or a Lobsterman (As both autopsies mention plastics integrated into their bodies). This fixes the (unlikely) potential issue where you don't have any dead Deep Ones a few months into the game when they disappear.

Wishlist/Todo - Feedback, suggestions and contributions for the below are welcome!

* UFOPedia page for the Plastic Plated Diving Suit. Ideally this would be based on the Diving Suit page, but there ISN'T ONE!.

* Differentiated Battlescape Paperdoll for the Plated Diving Suit is probably a good idea.

* Fix prerequisites for Ion Armor. You can't figure out how to make powered armor until you've interrogated a Deep One terrorist that has questionable intelligence and appears to make no use of technically-powered armor. What? I'd like to change this to something sensible and less broken, but I'm not sure what I could change it to without disrupting the balance of the game. A Technician alien would make sense, but they're too common. Is it possible to setup so you have to interrogate _several_ technicians to unlock the secret?

* I'm considering making Aqua-plastics a prerequisite for Gauss technology, with small amounts being required for construction of Gauss weapons. That would help explain why your small team of scientists is able to develop it when the rest of human civilization has not, and why you command a market premium on Gauss weapons throughout the game.

* Translations are welcome! I've only supplied English text.