Do not require consecutive driveX.json numbers

[mbroz]

It would be nice if I can have two numbering sections for collected JOSN files, for example

• 1-99 for local disks
• 100-1000 for colledted data from others

Unfortunately, code now requires consecutive sequence for JSON naming, without any gaps.

Maybe just read all *json files and index it just by name-sorted offset?

Also name prefix (drive*) should not be hardcoded on multiple places.

[matszabo]

AFAIK numbering gaps should work fine now. It used to be an issue a few months then but I fixed it.

I'll definitely give the change a thought and try to come up with something more versatile.