Validate command classes on demand, with specific validation for each type of effect

[mbiannaccone]

second attempt at this one: Validate command classes on demand and not on init.

this time around we made every field optional, so that there are no validation errors on init for empty values.

and then for each type of effect, we have a custom validation based on the fields that we indicate are required for that type of effect.

note: tests will fail spectacularly, but i will address tonight/tomorrow