Add support for dynamic amount generator lines/cells
Remove deprecated Resource.getPricingVariable

Default getPriceCalculationOperandDict script calls getPricingVariable
type-based script directly if variable_additional_price is not 0.
Amount: for total price, acquire price on resource only if unset

When a user explicitely enters 0 on a Trade Model Line, total price must be 0
no matter what is set on the resource.
Amount Generator: typos
Do not generate amounts without any base_application

Before we dropped amounts with quantity=0 and we stopped doing that because
it broke expand. However, there's still one case when such amount can be
ignored, i.e. when there's no base_application set on the amount generator.