[gnome-calculator] Fixes #67: Use Mass instead of Weight

[Robert Roth <robertroth src gnome org>]

commit 5e71e7df8f99c6670d696fbab67f96ff884f24bb
Author: Robert Roth <robert roth off gmail com>
Date:   Mon Jun 18 19:13:15 2018 +0300

    Fixes #67: Use Mass instead of Weight

 lib/unit.vala | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/lib/unit.vala b/lib/unit.vala
index 66347d56..0bba560b 100644
--- a/lib/unit.vala
+++ b/lib/unit.vala
@@ -30,7 +30,7 @@ public class UnitManager : Object
         var length_category = default_unit_manager.add_category ("length", _("Length"));
         var area_category = default_unit_manager.add_category ("area", _("Area"));
         var volume_category = default_unit_manager.add_category ("volume", _("Volume"));
-        var weight_category = default_unit_manager.add_category ("weight", _("Weight"));
+        var weight_category = default_unit_manager.add_category ("weight", _("Mass"));
         var duration_category = default_unit_manager.add_category ("duration", _("Duration"));
         var temperature_category = default_unit_manager.add_category ("temperature", _("Temperature"));
         var digitalstorage_category = default_unit_manager.add_category ("digitalstorage", _("Digital 
Storage"));