Don't include <iostream> in C++

[Teemperor]

The imported objects aren't used and there seems to be no
dependency on the includes of in the code.

Also, including < iostream > in libraries is bad practice and some
projects completely forbid doing it (such as LLVM) because it
does some nasty static initializations.

[andreasabel]

I am sorry you did not get a reply for your PR for almost a year. There was simply no maintainer to look into this.

Would you be willing to rebase your PR onto the latest master? I suppose the travis checks would then succeed.
Another thing is to run the test suite (currently not automatic). This is done as follows:

cd source
cabal install 
cd ../testing
cabal install
bnfc-system-tests

(assuming .cabal/bin is in your PATH).

[andreasabel]

Thanks @Teemperor, I merged it now.