Comment 5 for bug 1822316

Since I was just digging through this, a reminder on the status quo of the convert field:

The default convert for a component needs to be 1.
The default convert for a component *pin* is 0, meaning "applies to both converts"

The code could be better-commented about this, because it's easy to interpret the comments around the convert property to mean that components should have a default convert of 0, but currently only values of 1 or 2 are valid.