------------------
- [composite] Implement NumPy-based compositing functionality.
- [composite] Support blending modes other than dissolve.
- [composite] Support blending in RGB, CMYK, Grayscale.
- [api] Introduce NumPy array export method.
- [api] Drop deprecated methods from v1.7.x such as `as_PIL`.
- [api] Deprecate `compose` method.
- [compression] Rename packbits to rle.
- [compression] Improve RLE decode efficiency.
- [tests] Additional compositing tests.