Add options for not doing Windows-specific rules, not truncating

[flotwig]

I wanted to use this in the context of a web application which saves files on a GitHub repo (flotwig/markdown-notebooks) so I didn't need or want the parts that applied only to Windows filenames. So, I added an option to disable the last 2 regexes that are applied that are Windows-specific.

I also added an option to disable truncation, just for the sake of having some more options. :)

I added unit tests for the new functionality along with a switch for test.js to just run the unit tests. All tests pass, and this doesn't change the behavior the exposed API or the internal sanitize API for existing users.

[joelmukuthu]

Hi @flotwig, thanks for picking this up. I think a nicer way to add this functionality is adding a target option (perhaps an object with unix and windows properties, as boolean flags), see the discussion in #11 and #9 for the motivation. Particularly, the naming of that option needs to reflect that one is sanitizing for a certain environment, and not necessarily the environment they're on. target is just one suggestion :)

[flotwig]

That sounds good. So I make sure I get this right, the unix flag would basically only target the third regex for .. and ., since the other two are multi-platform?

[joelmukuthu]

Hmm, I'm actually not sure that . and .. are valid on windows. @parshap, you probably know more on this? :)

[joelmukuthu]

Also, @parshap, is the 255 max-length a thing on all platforms?

[jackycute]

~~I'm using macOS 10.13.6 and my volume filesystem is APFS, the longest filename length looks like 241, not 255.~~

I was wrong, it is 255 but includes the filename extension (means XXX.md the .md parts will be counted in).