Changes:
- implement different image scalers:
* crop: Crops out an area of the size of the placement size.
* distort: Distorts the image to the placement size.
* contain: Resizes the image to a size <= the placement size while keeping the image ratio.
* forced_cover: Resizes the image to cover the entire area which should be filledwhile keeping the image ratio.
If the image is smaller than the desired sizeit will be stretched to reach the desired size.
If the ratio of the area differs from the image ratio the edges will be cut off.
* cover: The same as forced_cover but images won't be stretchedif they are smaller than the area which should be filled.
- cache transformed images
- speed up drawing images by using shared memory / Xshm
- reuse already loaded images
- reduce import time of the python library
- replace pillow with pillow-simd as it seems to be a lot faster
- synchronous drawing: allow to specify moments a redraw has to happen on
- remove message on images: "Multi pane windows aren't supported"
- Some bugfixes