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.
Because of the way digging times is implemented in Mineclone2, it is
possible for the digging times of efficiency enchanted tools to become
outdated.
This fixes that by automatically updating the tools tool_capabilities
after each time the tool is used.