Top AND Bottom Support interfaces with Substitute Material Control

[BladerunnerxRC]

I envision having the same control on the bottom as the top of support structures, especially when choosing the interface material.

Application and benefit: Support filament materials allow for the clean separation of the support where it is not possible to 'support on build plate only.'

Problems and Issues:
Use support filament where you don't want the primary filament used in supports to adhere to the model at the bottom. Currently, the only option is using the support material filament for the entire support, which is wasteful, adds a tremendous amount of time to printing from filament swaps, and becomes costly.