This commit changes the style of tes3mp serverside scripting mods. Short list of changes:
* Break compatibility with old server mods
* OOP style lua API
* Basic dependency checker, allowing the installation of multiple server mods without changing configs
* Remove support for C++ plugins
* Change outdated LuaBridge to [sol2](https://github.com/ThePhD/sol2);
* Support GCC, Clang and MSVC compilers
* New environment variables: "TES3MP_SERVER_DIR" and "TES3MP_SERVER_USERDIR";
* New entity "Command controller" for registering new chat commands;
* New Event system
* Simplified Timer API
* All Lua mods now run in their own environments
* Add global namespace - Data that can be used for communicating between mods
* Player and Actor inherit base class NetActor
OnPlayerCellState and OnActorStatsDynamic are now removed as callbacks.
The old OnCellUnload is now renamed into OnCellDeletion.
OnCellLoad and a new OnCellUnload relating to a specific player's load/unload are added.
