Use long instead of int in offset and size

[seclerp]

To prevent overflow for large file sizes

[seclerp]

This also requires big changes in the defragmentation algorithm, so implementation will greatly be changed

[liesauer]

need large file size here

[seclerp]

Hi @liesauer, unfortunately, I don't have much time to implement this one. Maybe I will release 2.1 with such functionality included, but I don't have any estimation for you. PRs are welcome :)