added ability to set ID field name for display table

Ok, so another one (this time I think you may actually agree with me, since it's basic :smile: )

So, I prefer using clear id names (like c5 does), because it makes queries easier. I'm porting a project from using all `id` for my pks, and I realized the display table wasn't working. While there is a private id field... it can't be changed externally on a call by call basis.

Thus, this tweak, to be able to change the id field.