Added CLI option to show line numbers for errors

[fkarg]

Tested/written for usage with Markdown.

• Fuzzy matches based on rough location estimate
• Approximates line number in source file
• Computationally expensive for large files

[Findus23]

Hi,

This is the only of your changes I am not sure about if I should merge. I honestly never had the need to know the line number of the error (a search in the text editor shows it quickly most of the time) and with the MD/HTML/TeX/etc. conversion it wouldn't work in most cases anyway.

I merged 328d3dadceda1889c786656282788f3698a159a9 and e8598900c1881e50391f949904da9c70f5cccdb7, but if you are okay, I would just add a part in the documentation that mentions the existence of your code in case someone else is interested in this.

[fkarg]

Sure, sounds good to me