When Changing group size of competitors, ui get wrong

[xoco70]

When changing params that affects tree visualization like Prelim, winners x group, tree type, group size, number of areas, ui should warn user and then reset the previous generation

In this case, we just change group size from 3 to 5, and it results as a display anomaly

[webbrain-one]

Hi, I opened PR #73 to address this. It warns the user when parameters that affect tree visualization are changed—such as group size, prelim, winners per group, tree type, or number of areas—and then resets the previous generation. This should prevent display anomalies like the one when changing group size from 3 to 5.