Fixed fit_to_width: max_iter was ignored

[pteridin]

fit_to_width was previously a loop that ignored the parameter max_iter. That lead to infinite looping and refitting the table.

Also, on the first glance: The function seems to allow negative values in font-size. Should that be fixed as well?

[davidgohel]

Good catch, thank you! Thanks also about the possible negative font size, don't worry, I will add a warning/return if that happens.