[v5.0.0] Snapshot interpolation & friends

This major update introduces a whole bunch of new features and improvements, most notably snapshot interpolation (which allows to smoothen out the entities jittering that was caused by packages being spaced unevenly when latency is present), a friends request system, as well as some changes and improvements to the server-side physics system, including making it delta-time based

Also I was able to reduce the server's tickrate from 60 to 20 tps, which makes it much more performant and less bandwidth-heavy!

Advanced matchmaking functionality unfortunately didn't make it into 5.0, since I really didn't want to delay this major update for another few weeks. It is currently planned for v5.1 though!

Keep in mind, that as always I haven't been able to test everything, so please let me know of any bugs/inconveniences that you find in the framework!

Enjoy! :D
- Evoleo