Augmentation without using Kornia

[alexander-koch]

Implementing augmentations without using Kornia should be somewhat simple.
Kornia also just uses a displacement (meshgrid) + resampling under the hood.
A simple transformation matrix for e.g. flipping should be trivial to implement.
By doing registration and augmentation in one go, we avoid performing resampling twice, which should preserve more information of the original data.