stm 2.5.0.0 * Removed `alwaysSucceeds` and `always`, GHC's invariant checking primitives. (GHC #14324) * Add `lengthTBQueue` to `Control.Concurrent.STM.TBQueue` (gh-9) * Add `stateTVar :: TVar s -> (s -> (a, s)) -> STM a` combinator (gh-14) * Switched `newTBQueue` and `newTBQueueIO` to accept `Natural` as size (gh-17) * Switched `signalTSemN` and `newTSem` to accept `Natural` and `Integer` respectively (gh-17)