CheckBlockInteractionsRate export hook

[xoft]

Sounds reasonable, make an issue in the GitHub issue tracker for it (only the CheckBlockInteractionsRate()); try to be as specific as possible - if such hook existed, what parameters would it receive, what would the return values be, what would server do with individual return values, etc. Think of it as the documentation, like the one we have for the current hooks at http://mc-server.xoft.cz/LuaAPI/#hooks