Ipykernel

- Revert Backport of 605: Fix Handling of `shell.should_run_async` [622](https://github.com/ipython/ipykernel/pull/622)

**Note:** This release was deleted from PyPI since it had breaking changes.

- Changed default timeout to 0.0 seconds for stop_on_error_timeout. [618](https://github.com/ipython/ipykernel/pull/618)

**Note:** This release was deleted from PyPI since it had breaking changes.

- Fix Handling of `shell.should_run_async`. [605](https://github.com/ipython/ipykernel/pull/605)

- kernelspec: ensure path is writable before writing `kernel.json`. [593](https://github.com/ipython/ipykernel/pull/593)
- Add `configure_inline_support` and call it in the shell. [590](https://github.com/ipython/ipykernel/pull/590)
- Fix `stop_on_error_timeout` to now properly abort `execute_request`'s that fall within the timeout after an error. [572](https://github.com/ipython/ipykernel/pull/572)

- Rework `wait_for_ready` logic. [578](https://github.com/ipython/ipykernel/pull/578)