Wish: 2D PD plot with geom_rect, like ALE plot

Hi Christoph,

I am currently playing with all kinds of plots. For 2D ALE plots, it is very nice that it is possible to rescale axes by e.g. adding `+ scale_x_continuous("duration (log scale)", trans="log", limits=range(SGC$duration))` (I suspect that the limits would be avoidable if they hadn't been set with `scale_x_continuous` in the first place). This is quite useful for numerical features with skewed distributions.

For 2D PD plots, due to use of `geom_tile` instead of `geom_rect`, this is not possible: the rescaling does not resize the tiles. If the PD plot were created in the same way as the ALE plot (which might be doable with reasonable effort), 2D PD plots could be made rescalable as well.

Thanks for considering this wish.

Best, Ulrike