these were intended to be removed long ago, but other things came up and durability handling still depended on them.
long overdue... this isn't quite as extensible as the original api3/blocks system was, but this is primarily intended to replace Item->useOn(). If plugins want to use it it can be extended later on.
This should solve issues with people making GitHub PRs and having the web editor messing things up. GitHub Web Editor sucks :(
