Clarify path syntax requirements #3872
Description
It's not totally clear when writing code that deals with paths exactly what kind of path is expected, especially on Windows.
From reading through a fair amount of code, it looks like we usually expect native paths on Windows to look like C:/foo/bar/baz.txt. This is a little odd, since it's neither proper URL-syntax (it's not URL-encoded and doesn't start with a slash) nor an actual native path (since it uses forward slashes). That said, it's convenient to work with, so we should clarify somewhere that all internal paths should be in this format on Windows.
It also looks like there's a function FileUtils.convertToNativePath(), which appears intended to take a URL-style path (/C:/foo/bar/baz.txt), URL-decode it, and strip off the leading slash if there is one. This should probably be renamed to convertURLSyntaxToNativePath() or some such.