imprecise error message if image is too large

[svettwer]

Short overview
If you search for an image using find using an image that is too large, the error message is Searching for test.png failed. Reason: 'No match with required confidence 0.99. Best match: 0 at (0, 0, 810, 500)'.

In sakuli/sakuli#326 we discussed, that we would like to inform the user that his/hers sample was too large. We agreed that this is something that should be done in the upstream project. We'd like to introduce an Error object to the image recognition iterations (iterated via scales) to provide more detailed information why nut.js could not find a match especially when the image is too large.