Add a way to easily configure your mods

[mlem]

Sometimes mods need configuration. It would be nice to have it implemented here so mod developers don't need to take care of it.

Features:

• UI for Options Menu in Project Zomboid
• A convention, how mods save their Configurations (e.g. .properties)
• Easy to extend/implement a configuration (e.g. it will be saved only, if a mod implements a specific class e.g. StormModConfiguration)