Like the DOS 3.3 and ProDOS sector order issues, this change fixes the
physical order of the sectors on 13-sector disks when nibblized.
This change also adds tests for the 13-sector format to verify the
sector order.
One of the crazy things is that _Beneath Apple DOS_ failed me in this
instance because it doesn't discuss what happens to the last byte in
"5 and 3" encoding anywhere (AFAICT). I went back to the DOS 3.1
source released by the Computer History Museum here:
https://computerhistory.org/blog/apple-ii-dos-source-code/
The code is in `appdos31.lst` in the `POSTNIB` routine on line 4777.
* Adds an initial test for DOS format (.do) files
* Fix physical sector order when nibblizing DOS 3.3 ordered images
Before, when `.dsk` or `.do` images were nibblized, the resulting
track had the sectors in the wrong physical layout.
Now the nibblized track has the correct physical layout (all sectors
in order) which results in the correct DOS 3.3 layout as well.
There is also a test that verifies the order.
* Add another test for a non-zero sector
The new test checks that the values in physical sector 1 are those for
DOS sector 7.
* Add test for all physical sectors on all tracks
This change also removes a few stray console.log calls in the test.
