Stackview

New features
* The first four label colours correspond now to matplotlibs default colours when visualizing label images
* `merge_rgb()` for turning three images into a scikit-image style RGB image (channel axis is last)
* added `continuous_update` parameter in `interact()`

Bugfix
* Some labels where not shown (black) depending on the maximum number of labels

Bugfix:
* Imported libraries that were not listed as dependency

New features
* added `jupyter_displayable_output` decorator for static image output in jupyter notebooks


New features
* `interactive()` supports `bool` parameters using checkboxes
* Support label images


Bug fixes
* Also non-numpy images (e.g. OCL-Arrays) are supported, which caused an error earlier

stackview depends now on ipycanvas and no longer on numpywidget. Visualization may look a bit different, e.g. image size on screen. The public API remains unchanged.

Bugfix:
* Slider positions / maxima were wrong in some cases (thanks to Jordão Bragantini JoOkuma for reporting and fixing)