Add ability to set default values for query combo boxes

[grantfitzsimmons]

In the same vein as #3994

This would be a very nice addition that has been requested several times.

Requested By: SAIAB and others

[grantfitzsimmons]

Requested by: Eyal at University of Jerusalem

I want to set the default of the storage in the Vasculars collection to "Berman, 308, Vascular", but the combo box does not simply get a 'default=' attribute. I tried to set it as plain text or by its ID (10) and it does not affect the result (stays blank upon loading).

[grantfitzsimmons]

Added in #3994