Consistently use uint32_t for deviceid

There were a handful of places that incorrectly used signed values for the
deviceid.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Improve handling for old XML files in Uemis downloader

In order to work in the most expected ways for people who have used
a version of Subsurface that didn't store the deviceid in the divecomputer
we relax the testing for when a divecomputer entry is assumed to match the
current divecomputer.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>