This patch:
- teaches test runner to understand custom argument spelling, e.g. `--file=evalu` and `-j10`
- fixes `--file` filter to actually focus file paths instead of focusing
all tests with given path
This patch re-implements matching and reporting for test runner.
Among other improvements:
- test failures now show a short snippet from test
- test failures now explicitly say what received and what was expected
- `expect.toBe()` now does text diff when gets strings as input
- `expect.toEqual` now does object diff
