Added configuration options for vertical speed units.

Some people (free divers) are loving ft/s or m/s units for vertical speeds.
Now they can choose between /min or /s in the configuration (only Qt UI).

Signed-off-by: Patrick Valsecchi <patrick@thus.ch>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Use the same conversion grams->lbs in dive and equipment list

Subsurface stores weight values in grams. When displaying lbs,
the dive list was not rounding the converted weights up, but
rather truncating the value at the decimal place. The equipment
list was rounding the converted weights up. This gave two
different displayed values for the same weight value.

Signed-off-by: Benjamin Fogel <nystire@gmail.com>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Correct spelling of "weight" throughout the code.

"Weight" was misspelled "weigth" in several places in the code
and comments.

Signed-off-by: Benjamin Fogel <nystire@gmail.com>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Added the .ssrf extension to the open dialog filter.

Fixes #205

Signed-off-by: Patrick Valsecchi <patrick@thus.ch>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>