Reactive Slick

Here's the ongoing work on Reactive Slick.

/cc @cvogt for review later
I'm not 100% sure about anything when it comes to the Java Memory Model but the spec does not mention any situation like that. There would have to be some further explanation if "volatile read" really meant "volatile read (unless that compiler can optimize it away). The examples shown in the spec would also be wrong in this case because they don't show enough context to know that the whole thing could not just be optimized away.