Reset the Retry button on exit of the Download from divecomputer
page. So, it it not reset wehen swiping this page away, or
cancelling a running download, but resetting it on accepting
downloaded dives.
As we do not have real error reporting (from download failures),
this all is a little arbitrary. Another "fix" could be, not
changing the button text at all.
Further notice, this is not specific iOS, but also Android.
Fixes: #895
Signed-off-by: Jan Mulder <jlmulder@xs4all.nl>
59f86a06ad