Doesn't properly handle max_num and min_num

[unexceptable]

Doesn't affect me just yet, but while on save it does complain, it doesn't tell you what is wrong, just "Validation errors". And unlike the standard InlinePanel the gui doesn't do anything to tell you that there is a limit.

We should make the gui properly gray out or hide add more buttons on reaching max_num, and have the validations errors properly render as to exactly what is wrong in general, but mainly for min_num (since doing that in the gui is harder).