Reset libdivecomuter import canceled state

Once the process got cancelled once we never reset the flag.

Fixes #82

Initial-fix-by: Jef Driesen
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

qt-ui/downloadfromdivecomputer.cpp

@@ -335,6 +335,7 @@ static QString str_error(const char *fmt, ...)
 void DownloadThread::run()
 {
 	const char *error;
+	import_thread_cancelled = false;
 	if (!strcmp(data->vendor, "Uemis"))
 		error = do_uemis_import(data->devname, data->force_download);
 	else