Normalize drive letter

[MLoughry]

This is a follow-up to #2149.

I did not realize true-case-path did not normalize the drive letter, which can cause the same issues as described in #1895. The project does not seem to be maintained any longer, so I've removed the dependency and copied the code here with one small change to normalize the drive letter.

[nschonni]

Due to the license, we can't just copy/paste this in https://github.com/barsh/true-case-path/blob/master/LICENSE
The next major of node-sass will also likely be dropping all our custom download and binding code for node-pre-gyp, so I'm going to close this

[MLoughry]

Hmmm. Your repo, your call; but the code for that package is sourced entirely from a StackOverflow post. I'm not sure how they can claim license over it.

https://stackoverflow.com/questions/33086985/how-to-obtain-case-exact-path-of-a-file-in-node-js-on-windows/33139702#33139702

[MLoughry]

Is there a timeline for the next major version?

[nschonni]

Hmmm. Your repo, your call; but the code for that package is sourced entirely from a StackOverflow post. I'm not sure how they can claim license over it.

🤷‍♂️ barsh/true-case-path#1

For the v5 stuff, we're discussing it over in #2111
I think the main thing is getting libsass to cut a stable 3.5 release