Replace fake player code with fakelib

[OgelGames]

Replaces the fake player code with fakelib's fake player.

https://content.minetest.net/packages/OgelGames/fakelib/

[SmallJoker]

A few weeks ago I wanted to implement the fake player API in the engine using a detached RemotePlayer so that such implementations would no longer be necessary. Unfortunately that addition would require special handling in (my option too) many functions.

For the time being I suppose it's easiest to rely on a "proper" Lua implementation. The code looks good. I'll give it a try by the next opportunity.

[SmallJoker]

Works. Would you please be so nice to mention this dependency in the README.md? It's the only hard dependency, so having it listed there would be very helpful if someone wanted to install it manually (e.g. server owners).

[SmallJoker]

Thanks. Will merge in a few days unless there are objections.