fix long standing fusion bug in enumFromTo_double and improve baseline testing tooling

special thanks to @amosr for helping figure out the correct fix

I moved the tests into the main cabal, so they can be invoked by cabal test, and updated them to use quickcheck 2.7

also cabal test (and thence the test suite ) will now be invoked by by travis ci on every one. (doing the same for cabal bench is left for some other time)