Warn users who navigate to a script while Greasemonkey is disabled

[arantius]

It seems people manage to accidentally click on the monkey toolbar button and/or don't know what it does. Even when they figure out posting to -users and even when they're given the documentation that explicitly spells out the steps to fix it, they sometimes have trouble.

Add a notification bar, like that which shows when doing view source, when navigating to a script while Greasemonkey is disabled. To re-enable Greasemonkey. And perhaps also install the script?

[jerone]

Jeej for user friendly.