Implicitly add (assume) file extension

[asbjornu]

Is your feature request related to a problem? Please describe.
I'm considering moving from HTMLProofer to htmltest due to its superior speed, but can't get htmltest to work for my Jekyll-built site since links to internal files omit the .html extension. In HTMLProofer, this is remedied by setting the configuration property assume_extension to .html.

Describe the solution you'd like
It would be nice if htmltest, like HTMLProofer, was able to implicitly add (assume) a file extension to internal links.

Describe alternatives you've considered
I did some searching to find similar issues and found #60 which is related, but not the same issue (and also not resolved).

[aepfli]

i just stumbled upon the same issue - this would be a really cool addition

[nickvigilante]

I agree. We've been told to use pretty URLs to help boost our site SEO.