This commit fixes an issue were tools enchanted with both efficiency and
unbreaking would loose the effect of one of the enchantments in some
conditions.
This adds the metadata field "groupcaps_hash" to tools enchanted with
efficiency. This value contains a hash of the groupcaps field in
tool_capabilities. This value gets compared to the expected hash value
to determine if the tools tool_capabilities should be updated according
to commit af31f8189e8e5c2b.
This commit makes efficiency more efficient.
The function mcl_autogroups.get_groupcaps is used by mods to get the
groupcaps for tools with efficiency enchantments. This function is used
by mcl_enchanting when enchanting tools with efficiency.