Use ALT-S, not CTRL-S to save.

In my experience, CTRL-S opens the browser's Save Page dialog. Since that takes focus, it does cause the current edit to save, but it's not ideal. ALT-S is the key to use.
Merge pull request #361 from JayBazuzi/master

Change default pages to suggest ALT-S, not CTRL-S. (See Issue #126)