`repeat` helper moved to `Repeat` namespace

New `repeat` helper - successor of retry helpers

Testing in multiple PHP versions

New helper `ChunkIterator`

Now hooks accepts catched exception as argument

New Retry class helper with more features than function helpers

- Supports specific exception catching (instead of dummy Throwable catch)
- Supports hooks in catch block
- Getters/setters for all options

New retry helpers

- `retry_timeout` - Repeats the callback until the answer is returned or timeout occurs
- `retry_count` - Repeats the callback until the answer is returned or the callback starts N times

New common helper `get_by_path` and `req_by_path`

ext-json required by tests

Removed a duplicate TO_INT conversion from `tokenize`