Strip FAT sectors beyond end of file

[sftse]

This fix was prompted by errors of the form Malformed FAT (FAT has 1770 entries, but file has only 1675 sectors).

Similar to #65 this is because mislabeled FAT sectors beyond the end of the file:

    header: Header {
        version: V3,
        num_dir_sectors: 0,
        num_fat_sectors: 14,
        first_dir_sector: 1631,
        first_minifat_sector: 0,
        num_minifat_sectors: 3,
        first_difat_sector: EOC,
        num_difat_sectors: 0,
        initial_difat_entries: [
            1661..=1674,
        ],
    },
    difat: [
        1661..=1674,
        95 FREE,
    ],
    fat: [
        1..=2,
        EOC,
        4..=1630,
        EOC,
        1632..=1660,
        EOC,
        109 FAT,
        22 FREE,
    ],

It also might make sense at this point to just truncate the FAT if it is longer than the number of sectors, instead of stripping off special cases from the end. Is there really anything else one could try if they dont match?

[mdsteele]

Thanks!

[sftse]

Thanks for the quick turn-around! Can we have a release?

[mdsteele]

Published as v0.12.1.