Merge the initial Garmin Descent Mk1 support.
This actually works well enough to be useful, even though there are a
few ugly details yet to be sorted out.
The download itself is fairly complete, but all event handling is
currently missing (warnings, gas changes, things like that).
Also, because of how libdivecomputer works, the "downloading" of dives
is entirely separate from the "parsing" of dives in the libdivecomputer
world. And that is actually problematic for the Garmin Descent
downloader, because you actually need to parse the data to even figure
out whether it's actually a dive at all!
The Garmin Descent is also a fitness and general excercise tracker, so
people can (and do) use it for other sports than just diving, and so the
activities we download may end up not being dives at all, but other
events.
But before we parse them, we don't know, and we aren't really supposed
to parse them until after we've passed the data to the application and
it passes it back for parsing. Nasty chicken-and-egg problem there..
So right now non-diving activities will just show up as very short
and/or shallow dives.
This is fixable by just parsing things an extra time, but I really wish
libdivecomputer would just stop thinking that downloading and parsing
are separate events.
* garmin-descent:
Add dc_usb_storage_open to the symbols list
garmin: only record gasmixes for cylinders that aren't enabled
garmin: don't emit fake device info and vendor event
garmin: add support for downloading gas mixes
garmin: add GPS coordinate data and improve parser_get_field() reports
garmin: actually start using the parsed data
garmin: turn all the remaining unrecognized fields into DEBUG messages
garmin: add a lot of new field definitions
garmin: teach the parser to show undefined values for unknown fields too
garmin: fix file length header parsing
garmin: teach the parser about invalid values and more dates
garmin: some fields are defined in all message types
Garmin: start parsing definition records
Garmin Descent Mk1: flesh out the actual downloading part
Add Garmin Descent Mk1 skeleton
Add 'USB storage' transport enumeration
f6ea5f514a