* Load client-side mods into memory before executing them.
This removes the remaining filesystem access that client-sided mods had and it will hopefully make then more secure.
* Lua Virtual filesystem: don't load the files into memory just scan the filenames into memory.
* Fix the issues with backtrace
* fix most of the issues
* fix code style.
* add a comment
* client side mods are located in clientmods/
* move builtin/preview.lua to clientmods/preview/init.lua as a preview mod
* refactor ModConfiguration class to work properly with client and server using child objects
* move some Server constructor mod load code to ModConfiguration to reduce code duplication between client and server
* remove mods.{cpp,h} unused functions
* use UNORDERED_SET instead of std::set in some modspec storages
* squashed: CSM: Implement register_globalstep
* Re-use fatal error mechanism from server to disconnect client on CSM error
* Little client functions cleanups
* squashed: CSM: add core.after function
* core.after is shared code between client & server
* ModApiUtil get_us_time feature enabled for client
* rename GameScripting to ServerScripting
* Make getBuiltinLuaPath static serverside
* Add on_shutdown callback
* Add on_receiving_chat_message & on_sending_chat_message callbacks
* ScriptApiBase: use IGameDef instead of Server
This permits to share common attribute between client & server
* Enable mod security in client side modding without conditions
