Changelog for monte-carlo-0.3

Changes in 0.3: * Add strict versions of sampleSubset, sampleIntSubset, and shuffleInt. * Port to vector-0.6.0. * Add Exponential and Levy alpha-Stable distributions. * Add Summary.Bool for indicators. * Move Summary to Data.Summary * Introduce `repeatMC`, which produces an infinite (lazy) stream of values, and `replicateMC`, which produces a lazy list of specified length. * Remove `repeatMC/repeatMCWith`. * Build fix for 6.8.2 from Robert Gunst. * The function `sample`, `sampleWithWeights`, `sampleSubset`, and `shuffle` no longer require that you explicitly pass in the length. * The pure RNG is now a newtype, so you can't use the functions from GLS.Random.Gen on it anymore. * The internals of the monad have been cleaned up. IO is used internally instead of `seq` calls and `unsafePerformIO` everywhere. This results in a modest performance boost. Changes in 0.2: * More general type class, MonadMC, which allows all the functions to work in both MC and MCT monads. * Functions to sample from discrete distributions. * Functions to sample subsets