Make sure process starts with no output

Min spare processes fix and shutdown fix

PHP doesn't guarantee destructor order on shutdown and occasionally, the pool process may be shut down before the pool has time to tell it to exit.

Ignore .vscode in bundle

Fix blocking reads; Better error handling

- Fix process not being closed on exit message failure.
- Fix blocking reads.
- Add error handling to writes.

Error and EOF fixes

- Fix unexpected EOF exception on close.
- Fix standard error output across requests.

Manage number of spare processes and kill processes in destructor

Initial commit