implements:
- splitting tiles into bricks
- raster-scan tiles
- uniform and non-uniform splits
- all tiles/bricks in one slice
- each brick one slice
- PPS syntax

missing:
- rectangular tiles
- slice header syntax

further todo:
- rework slice mode 2 to use multiple tiles for byte size matching
- lots of renaming (tile->brick)

- tiles are in the VVC spec for 3 meeting cycles now
- cleanup helps with adaptation for tiles to current draft