Changing split type does not convert values

[krokosik]

Currently, when adding an expense, the value is set for 1 in equal split and 0 otherwise. Unfortunately, when changing the split type, values are not converted to keep the amount and what is more annoying, transfer the useless 1s.

I noticed in the code that there is a function for handling that, but it is not called for some reason, so I thought that it should be brought back and called on SplitType change.