Merge pull request #218 from jorisdral/jdral/revise-io-sim-1.8
`io-sim-1.8` fails to build with `io-classes-1.7` and earlier versions
`io-sim-1.8` fails to build with `io-classes-1.7` and earlier versions
`InspectMonad` was renamed to `InspectMonadSTM` in `io-classes-1.8` and `io-sim-1.8`. `io-sim-1.8` fails to build with `io-classes-1.7` and earlier, so those versions should be omitted from the build dependencies. Alternatively, some CPP could be added to use either `InspectMonad` or `InspectMonadSTM` depending on the version of `io-sim`.