v1.1.0 gotta-kill-'em-(all)!

This release brings proper support for flushing jobs and leverages ZLE watchers for notifying (instead of kill signals) on zsh versions >=5.1.

Changelog

• Previously async_flush_jobs only killed the immediate child running inside a worker. If something else was executed by that child, it would continue running until completion. This was changed to instead send a TERM-signal to the entire process group thus allowing all task to exit gracefully.
• ZLE watcher replaces the kill -WINCH method of notifying when a job is complete whenever it is available (done through feature detection). Since zsh 5.1 zpty workers return the fd that was created for them and because of that we can attach a ZLE watcher to the fd that is triggered on output.
• Fixed an issue where async notify didn't work if setopt localtraps was set.
• Code cleanup

Full changelog: v1.0.0...v1.1.0