Add filterWithKey and bump classyprelude cabal version

[L0neGamer]

closes #218

also adding dist-newstyle to the gitignore list

@BebeSparkelSparkel

[BebeSparkelSparkel]

@L0neGamer Please add to mono-traversable/ChangeLog.md

[BebeSparkelSparkel]

@gregwebs When working with snoyberg on PRs he did not have me up the prelude versions when functionality was added to mono-traversable. What is your opinion on this?

Considering that ClassyPrelude.hs imports with hiding it does not make sense to me to up the version if the dependencies export more.

[gregwebs]

yeah classy prelude only needs to be bumped if it is exporting new things.

[BebeSparkelSparkel]

The version of classy-prelude should remain unchanged.

[L0neGamer]

the version is unchanged, I used the wrong language; the cabal file was updated because stack was run at some point.

[BebeSparkelSparkel]

@L0neGamer #234 fixed the classy-prelude cabal version. Try rebasing on master and ensure that classy-prelude/classy-prelude.cabal is unchanged and this should be ready to pull.

[BebeSparkelSparkel]

@L0neGamer Thanks for the help!
@gregwebs Appreciate the input!