NF: Adding field seperator selection in output

[EitanHemed]

Following this feature request, this pull request will allow passing the data delimiter selected on PsychoPy, when converting the experiment to PsychoJS.

Note that the changes are not implemented yet on the PsychoPy end, and psychoJS.ExperimentHandler._field_separator is an undefined property. Thus the expected behavior is that the default (',') field separator will be selected.

[TEParsons]

Broadly I like your thinking, but I think it's better for cross-language parity if the delim is an input when creating the experiment handler rather than being in expInfo. Being in expInfo means that it will appear in the data file and (if we don't otherwise handle it) the participant info dialog.

What if instead of looking for field_separator in extraInfo, ExperimentHandler simply had an attribute .field_separator (like what you extract to here) which defaults to "," if not otherwise set? Then in the compiled code from the app we can do psychoJS.experiment.field_separator = %(Data file delimiter)s

[EitanHemed]

Thanks for the feedback @TEParsons, i think the current changes should do it and not putting it in expInfo is more elegant.
BTW, as far as i could see entries in expInfo which begin with an underscore are excluded from the participant info dialog.

[TEParsons]

Spot on, this looks great!

I've tested the Python end and confirmed the code is generated fine, @apitiot @lightest is there a way to test the JS end that this value is used correctly by the experiment handler?