Remove space after comma for TupleXX.toString()

It is better to save some bytes when writing the output. Users can always overwrite to `toString()` if they want.

Author: Robert Metzger <rmetzger@apache.org>

Closes #118 from rmetzger/benchFixes and squashes the following commits:

cb8a251 [Robert Metzger] Remove space after comma for TupleXX.toString()