Add run extension

[neclitoris]

It was pointed out to me that IS# results are way off. Indeed, +90% coins at level 4 seemed excessive.

After investigating, I noticed that these results happen because of the way you compare a mastery to the baseline. You normalize results of a wave X against the wave that happened at the same time in the baseline run, which means you compare IS#4 wave 4000 against baseline wave 3100-ish, and use that as the basis for your calculations.

I didn't want to get too deep into modifying your code since it's quite entangled and the potential to mess things up is there, so I created a flag that automatically extends runs to the same length based on their average rewards. This way the legend displays correct values for both relative increase and ROI per stone (I didn't come up with a simple and non-intrusive fix to the second one).