fixed some test case errors
changed from deprecated `contains` to `in`
Merge pull request #357 from tanmaykm/contains

Moved from `contains` to `in` and fixed a few tests
Update 03_io.md

Decimal default specified as comma, when default is actually period.
Merge pull request #358 from randyzwitch/patch-1

Update Documentation for I/O section, decimal character
Make benchmarks run again

DataStream benchmarks disabled, since they don't work and the
corresponding tests are also disabled