* Windows platforms prior to Windows 10 1703 cannot access any logical partition besides the
first one (we don't even get a volume for those).
* This fix enables the use of physical + offset for ext# formatting to work around this,
which is file since we don't actually need to mount the partition.
* Also fix ext2fs_open2() not handling normalized versions of Windows drive paths ("\\?\...")
* Also fix an issue where we would make the drive letter unavailable after formatting a
standalone partition to ext#.
* Also ensure that we return an error if the drive we attempt to locate a partition on
through an offset does not match the currently selected one.
* Also remove some unused calls in drive.c.
* Closes#1374
