Two small features: Auto-save and auto-reload

I end up using a lot of editors when I'm developing, and so I like to have two features available:

1. Auto-save on loss of focus. I really, really don't want to have to remember to save everything before swapping away from one editor to another.

and

2. Auto-reload when an external file has been modified.

This patch adds both of these features as options (default disabled):

editor.saveonfocusloss = true
editor.autoreload = true

Tim