Draft for generic support

[foyoodo]

Hi, I wanted to ask if there are any plans to add generic support to FlexLayout. This would allow for more flexible usage, such as the following code example:

extension Flex where Base: UILabel {

    var text: String? {
        get { base?.text }
        set { base?.text = newValue; markDirty() }
    }
}

I’ve made some changes to the code, and I’m submitting this as a draft for review. Let me know if this is something that could be considered.

Thanks!