Initial support for Mares import

This import is based on one sample I received. It was exported from some
Mares software. Imported data is somewhat limited, but we do get the
depth and temperature profiles. (I would love to receive some more
sample logs to validate the import and to enhance the data we are
grabbing.)

Signed-off-by: Miika Turkia <miika.turkia@gmail.com>

core/parse-xml.c

@@ -2213,6 +2213,7 @@ static struct xslt_files {
 	  { "manualcsv", "manualcsv2xml.xslt", NULL },
 	  { "logbook", "DiveLog.xslt", NULL },
 	  { "AV1", "av1.xslt", NULL },
+	  { "exportTrak", "Mares.xslt", NULL },
 	  { NULL, }
   };