Feature request: Per-world configuration

[SecretOnline]

While this mod has a disclaimer saying "don't use this on competitive servers", this mod could help prevent sticky situations by automatically switching settings based on context. The most obvious context (and probably the only one I will implement) is when joining different worlds or servers.

This will almost certainly need the configuration rewrite, as options.txt is not the right place for anything like this (and it's also not the right place for the mod's config as it is but oh well).

Requirements:

• The ability to have different settings on different worlds and servers.
• A way of specifying whether a world uses the default config or a custom one.
• A default configuration profile that is copied when adding specific configuration.

Out of scope:

• Preset settings for common servers.