Major commit to the constraint solver

Friends I've pushed branch wip/new-flatten-skolems-Oct14. (It has some rebasing near the top.) It branches off master some a few days ago; i.e. it is almost completely up to date. Can you try building it? I want to push it to HEAD, but would like some independent validation first. Three things don't validate for me: * Several tests fail with ioManagerWakeup problems: reported as Trac #9722 * ghcirun002 experiences stack overflow in the bytecode interpreter, but so does HEAD: Trac #9741 * I get an odd wibble in safePk01, see this threadhttps://www.haskell.org/pipermail/ghc-devs/2014-November/007065.html with Edward I'd like to push to master soon. Thanks Simon