The windows version doesn't handle non-ascii characters in command line arguments correctly

[joesiltberg]

Can be reproduced for instance with the csv test in the test suite by adding Swedish characters to the cn of the groups in the groups.csv file and then adding a limiter (which uses Swedish characters) to the spec.json for the csv test.

We should probably use wmain instead of main. The easiest solution might be then to convert argv from UTF-16 to UTF-8 so the rest of main can work in the same way regardless. Currently we're using boost::program_options::command_line_parser which assumes char. Switching to wcommand_line_parser, but only for Windows, might get messy.