Better log-ability

[saschpe]

Is your feature request related to a problem? Please describe.
None of the various load methods allow to inspect error conditions, i.e. why an image load failed. At the moment it's next to a black box. Interestingly, there is no log output either.

Describe the solution you'd like
Probably the easiest solution is to let load() methods accept another lambda that is called in case of errors, i.e. onSuccess = (Exception) -> Unit = {}

[colinrtwhite]

To get access to the failure Exception you should add a listener:

imageView.load(data) {
    listener(
        onError = { _, error ->
            // Handle the error.
        }
    )
}