Some items, like shulkers or books, can have so much metadata that the
corresponding item entity can not be serialized by the Minetest engine.
Without this patch, dropping such an item and then moving away crashes
Minetest, as it can not serialize the entity with serializeString16()
when unloading a map block.
The patch resets the overlong metadata of non-serializable item entities.
This avoids a crash and makes it possible to retrieve a “sanitized” item
without metadata when the mapblock containing the item entity is reloaded.
Originally sfan5 guessed the maximum possible item entity serialization size
that would not lead to a crash as 65530 bytes, but anon5 calculated it to be
actually 65487 bytes. This has been experimentally verified by erlehmann.
Group levels are now specified as a list of names when registering a
digging group. Digging groups which do not have specified levels will
support tools having two levels, 0 and 1 where 0 means the tool can dig
but not harvest the node and 1 means it can also harvest the node. If
more levels are required one has to specifiy them when registering the
digging group.
These changes are primarly made to make mcl_autogroup more efficient.
Previously enchanted tools required storing around 21 kB of metadata due
to the way the previous version of the mod was implemented. This caused
a lot of lag and a huge amount of network traffic. With the changes
enchanted tools won't require more than 1 kB of metadata.
The mod is also rewritten to use an API to register digging groups and
compute the groupcaps for tools. This will make it easier for modders
to register custom digging groups.
The mod is now split up into two parts. One part called "mcl_autogroup"
to implement the API for registering custom digging groups, and the
other part called "_mcl_autogroup" which contains most of the code which
has to be loaded after most mods.
