Immersive Cavegen

- Removed global cave width modifier and added individual cave width modifiers for each internal cave type.

- Made it so that the width modifiers can be negative as well.

- Made config auto-reload on world load/creation, meaning you can now edit the config while being in title screen, saving startup time. Note: Not all options can be edited at runtime as some take effect when the game is loading, but nothing can be done about that.

- Added option to prevent underground dirt from spawning.

- Added a set of options to allow to make certain internal cave types less common.

- Added option to prevent vanilla cavern spawning totally.

- Fixed error on first launch due to not finding config file before it's generated.