Gracefully handle server/client setting mismatches

[OpenBagTwo]

As called out in #35:

If a server sets n_discs to a value greater than max_discs, then all clients will, at a minimum, need to set max_discs in their config files to the new number. Otherwise they will receive an error when connecting.

This is an edge-case of pushing the mod to its absolute limits, but there are some great examples of mods that will detect config conflicts and offer to fix them then restart Minecraft.

This is not slated for the initial release, nor would I consider it super high priority.

[uczpre]

Give a setting to automaticly sync , as i suggested in some other issue that im to drunk to remember about.