Bug in scale recipe calculation by efficiency

[theophae]

I found a major issue in the scale recipe calculation tool. If you use some sugar or some extract in you recipe and you want to change the recipe efficiency by using the scale recipe tool, the original gravity will change whereas it should not. This is not noticeable if you don't have a lot of non mashable sugar in you recipe or if you change the efficiency for a few point. But this bug is very noticeable if you go from 70% efficiency to 50% for instance.

Enough talking ! I found this bug, but I also found the fix ;-) so please assign it to me.