Support Windows disk drives in the normalization algorithm

[ForNeVeR]

Currently, our normalization algorithm doesn't support the Windows disk drives at all. We should consider the disk drive (if present) to be ignored when normalizing path: it should be normalized regardless of the drive letter and its presence.

For example, consider this set of test cases:

    [InlineData("C:.", "C:")]
    [InlineData("C:./foo", "C:foo")]
    [InlineData("C:..", "C:..")]
    [InlineData("C:/..", "C:/..")]
    public void WindowsSpecificDotFoldersAreTraversed(string input, string expected)

We should support that and re-enable the corresponding test.

See TODO[#16] in the code when dealing with this issue.