Fix mistakes

[ivanpanch]

I have corrected some minor mistakes.

[barendgehrels]

Thanks a lot - looks very good - I'm basically OK (didn't run the tools myself)

[tinko92]

No objections to the changes. Should the commits be squashed into one, though?

[ivanpanch]

I have made some further changes, can you have a look? One last thing: There is Line height in SVG pixels, in case the text contains \n, but \n is not rendered verbatim here: https://www.boost.org/doc/libs/latest/libs/geometry/doc/html/geometry/reference/io/svg/svg_mapper.html