* Add `break-before` utilities
* Add `break-inside` utilities
* Add `break-after` utilities
* Add `break-before/inside/after` utilities to basic usage test
* Remove `break-before` and `break-after` utilities that have no browser support
* Rename `break-inside: avoid-column` utility to `break-inside-avoid-column`
* move `./tests/jit` to `./tests`
* make tests consistent
Abstracted a `run` function and some syntax highlighting helpers for
`html`, `css` and `javascript`.