Rewrite physics

Physics are not really accurate, I already started a rewrite once, but that was not the right approach. There needs to be a real rewrite with all features supported. They also need to be unit and integration tested (with all edge cases), so thousands of lines of testing are required.

So this would be the the final physics engine, it should cover everything. Some things to respect:

• Not just match, bit wise equality
• Test edge cases
• Extract from entity logic
• make as "flat" as possible
• refactor and improve as much as possible
• Integration testing
• Practical testing (with various anti cheats)

Related: #27 (closed)