Clojurians Log v2

Thanks to @pat this release ensures that Datahike compiles again to cljs. This is the first step to get Datahike running on cljs again. I am curious to hear what people would want to do with that.

We have released our improved constraint system (kind of like smart contracts) here https://github.com/datopia/invariant. Thanks a lot to @moe.aboulkheir for working with me on this over the years. It was part of our blockchain prototype "datopia" on top of tendermint. The general integration of Clojure into the transaction system of it is documented here https://github.com/datopia/abci-host, we might also release the combined prototype, but we did not get to finish it yet. The invariant system makes sense on its own though, and does not require any of the other bits. It is a fairly simple, but very powerful idea. You can think of it as transaction constraints written in Datalog itself, which allows it to naturally join against the database and pattern match in fairly complex ways. The constraints themselves are deployed as queries into the database for a specific attribute, and then automatically executed when this attribute is affected by a transaction. This code also contains a safe-guarding of function usage in the constraint logic, so you could allow users to deploy constraints.