add kerning toggle (-k)

[frankrolf]

addresses #6

[frankrolf]

I implemented your suggestion @benkiel, if you have time to check out the result I’d be grateful :-)

[frankrolf]

Did you get a moment to review this @benkiel, or should I just merge it?

[benkiel]

Yes, this works well! I would suggest that the toggle be -nk, as -k implies that kerning is on, but the nice output note on the pdf helps here

[frankrolf]

Thanks for taking a look!

I understand that the single-letter options may be ambiguous, however this also makes it possible to chain them.

For when you need to be explicit, there’s always the --kerning_off option:
https://github.com/adobe-type-tools/drawBotProofing/blob/main/textProof.py#L110