Priority Attribute To Sort Ports

[dannymate]

I would like some kind of attribute that can be applied to ports to specify what order they should be in. This will be a negative to positive integer. Defaulting to 0. Positive values mean higher in display while negative values display lower.

This probably won't be added as a portdata thing. CustomGeneration ports will be expected to output portdata in the order they want them to display and the priority attibute will apply to the whole group instead.