0.4 World generation upgrade

It's about time for another proper update for SSC. The changelog is down below, if you want to skip this text. I don't mind. This update is a bit smaller on content but a much needed one. Only ~170 commits, about ~6400 new lines AND ~17 bug reports from new testing team later, 0.4 is now ready for you guys. There are updates on art side, there has been refactoring, there has been few rewrites. At the end of all that, I also pulled few things from future update plans into 0.4, which are a bit out of current theme, but much needed ones. Few examples - rebalancing ship properties, collision based rockets, new part for AI to make it work better. 

A huge part of this update was the world generation rewrite. The old one was just one or two components in Unity and it got a bit difficult to manage it, both in code and in my head. So I rewrote the whole thing, many times and in many variations, and got it to a point where I can implement different variations of worlds. Now it has better performance AND it's really easy for me to work with it in the future. Basically, the new one is in stages. Each stage modifies, adds or removes stuff from an existing data set. At the end of it, the last stage populates necessary registries and bits depending on if we want to have universe preview or load in a new game.

Another quite huge part was to consolidate keyboard inputs. It had to be done to get bugs fixed. The game had loads of places where one input did multiple things at the same time or a bit delayed. When I implemented in game console to give more creative tool for me and you, it got really fun. Or when I added renaming of planets. Typing in letters "was" moved camera up, left and down. Or when name had a letter "p" in it, time slowed down. 

Speaking of keyboard inputs, the UI had some much needed change too. Some of you have interesting monitor sizes and even more fun resolutions, so UI scaling had to be done. With it, I had to switch from using old Unity components to a bit newer Text Mesh Pro they have. I wanted scaling to be so that you guys can select a scale factor from a slide but it caused too many problems and headaches. So I went with a fixed set of numbers - 0.5x, 0.75x, 1.0x, 1.25x, 1.5x and 2.0x. Hopefully these options give more options for those interesting setups. If not, do let me know and we will figure out something together. 

Before you get to the changelog, let's talk a bit about next version(s). Before I actually start coding 0.5, there will be 0.4.1 and 0.4.2. Those will be smaller ones with some tweaks and more content and hopefully will be released faster. Famous last words. Anyway, a few things from my list are time controls, settings in game view, upgrading console, visible orbits, different size planets and stars.

**Changelog**

[New]

- Rewrote world generation backend to make it easier to work with a world generation process.

- Updated world generation

- Implemented regions (needed for future update)

- Multiple stars, only 1 variation is currently in the game.

- Spaced out asteroids a bit more from each other.

- Asteroids are more concentrated in the middle of the universe.

- Changed how and where solar systems are generated.

- 1 planet/1 star systems have planet farther away from the star.

- Added 1024x1024 world size (shows how badly optimized stuff are, whoops)

- Showing world preview and it's numbers (Regions, stars and planets) in "New game" view thanks to new world generation backend.

- Added ability to rename things

- Rebalanced ship properties.

- Implemented collision based rockets.

- Disable "start game" button when world seed is not valid, e.g. not enough planets for the set amount of players.

- Added new information to ship build tooltips - description, ship properties.

- Added tooltip for top position number to show current standings.

- Converted Unity UI stuff to Text Mesh Pro.

- Added UI scaling option.

- Implemented in-game console.

- Added new satellite variation.

- Added new frames to explosion animation

- Updated some ship sprites with grayscale versions.

- Implemented weight system for AI node tree edges to make it less random.

- AI focuses more on attacking player when they conquer a new planet

- AI focuses more on attacking player when they are ahead of it with points

- AI focuses more on getting planets when it has a bomber.

- AI puts more focus on research when it doesn't have bomber yet.

- Allow to move Crabs and Haulers to anywhere. Previously they were only reacting to asteroids.

- Can now move camera by moving mouse to the side of screen.

[Fixes]

- Implemented new awesome event based input system to help fix various bugs with colliding inputs. E.g. pressing escape does about 3 different things at certain points.

- Fixed flipping a camera axis by scrolling too fast on osx.

- Set research scroll view to top.

- Store game statistics to show correct points and top list when loading a game. Applies to new games only.

- Fixed few existing sprites to make them look a bit nicer.

- Removed date prefix when showing saved game names.

- Allow player and AI to spawn in same solar system when world has not enough solar systems.

- Set auto targeting system behind cooldown when player gives ship an order.

- Change random seed when player opens up "New game" view again.

- Reduced default UI sound from 0.5 to 0.1.

- Moved fleet slot 0 to after slot 9.

- Automatically hide in-game event notification after a minute.

- Fixed box selection not working after mouse was clicked before.

- Fixed asteroid sprite pixel per unit. Made asteroids a bit bigger.

- Fixed ships with multiple behavior's (e.g. Haulers and crabs) doing odd things.

[Not-that-visible-but-mention-worthy-changes]

- Upgraded Unity from 2020 LTS to 2021 LTS.

- Renamed suns to stars in code.

- Implemented multiple world generation types.

- Detached world size from world generation size.