Update child repos to PSR-4 for git subs-plit
Miscellaneous `ExtEventLoop` stuff.

* Added `ExtEventLoop` to the event-loop readme file
* Added `ext-event` to composer suggestions
* Added messages to composer suggestions (suggest doesn't use version constraints)
Fix 100% cpu usage for idle StreamSelectLoop with no timers.
A null timeout must not be multiplied by an integer.
Fixes #275