Cleaned up and rebased "libdivecomputer-NG" branch

[Linus Torvalds]

Ok, I finally got around to cleaning up my subsurface changes, and
there is now a newly rebased libdivecomputer-NG branch at

   git://github.com/torvalds/subsurface-for-dirk.git libdivecomputer-NG

that I think is in good enough shape to be pulled.

That branch has the same requirement on the "Subsurface-NG" branch in
libdivecomputer, but has additionally:

 - many cleanups, including entirely removing the "ble_serial" code
(which in the old branch stayed around as dead code)

   The ble_serial code wrapped the BLE code in a serial emulation
layer, but now that libdivecomputer natively knows about BLE, there's
no point any more.

 - simplified history.

   I couldn't really split things up into lots of small changes (since
it's a flag-day for the new libdivecomputer interface anyway), and
instead the conversion history is just two commits: (a) convert our
custom IO implementation to the new libdivecomputer world order and
(b) hook it all in and use the new world order.

 - I added the fingerprint patch.

   Ok, so this has nothing to do with the new world order, and maybe
Dirk wants to handle this some other way, but it was part of my
testing and seems solid, and is technically about libdivecomputer (and
affects nothing else).

NOTE! I have *not* updated libdivecomputer itself. I looked at it, and
it all looks fine. I think Dirk should just use his "NG-test" branch
as-is (ie my NG update and merging in the libdivecomputer upstream
bugfix). But just rebasing it on top of the libdivecomputer OSTC3
bugfix would be fine too. But unlike the subsurface branch, there's
not really any big *reason* to rebase.

Dirk - up to you. And obviously, I don't know when you want to cut
over to the new libdivecomputer world order.

                Linus