`SymbolicDiscreteCallback` and `SymbolicContiniuousCallback` have different affect field names

[TorkelE]

Not a bug really, but an internal oddity that is probably a mistake.

The affects field is called affect for ``. Since it can hold several affects, affects should probably be used.

struct SymbolicDiscreteCallback
    # condition can be one of:
    #   Δt::Real - Periodic with period Δt
    #   Δts::Vector{Real} - events trigger in this times (Preset)
    #   condition::Vector{Equation} - event triggered when condition is true
    # TODO: Iterative
    condition::Any
    affects::Any

struct SymbolicContinuousCallback
    eqs::Vector{Equation}
    affect::Union{Vector{Equation}, FunctionalAffect}

Might be intentional, and have no impact on stuff. However, since I noticed I figured I should point it out. Feel free to close this issue whenever you want.

[vyudu]

This is breaking right? Should this go in v10?

[TorkelE]

Unless the old affect field is kept, yes. Personally, I am agnostic to whether this should be changed or not, but figured I should point it out at least so you guys in MTK can make a decision. If not, it might be good to put in a comment in the code pointing out whether this is an inconsistency or intentional and their is something distinguishing the two cases.

[ChrisRackauckas]

This isn't documented API so I think this wouldn't be breaking.