cabal2nix: normalize the package description string
cabal2nix: normalize the package description string

 * If the string contains only one dot, and that happens to be the last
   character, then we strip it.

 * Newline characters are stripped.

 * Double quotes are escaped.

bennofs/cabal2nix,psibi/cabal2nix,spencerjanssen/cabal2nix,gridaphobe/cabal2nix,jb55/cabal2nix,dmalikov/cabal2nix,Fuuzetsu/cabal2nix