An option to auto-save every time Play is pressed, or a Save-All-Changes button

This is in part due to the lack of good support for source control, but all the time in my company artists are setting up their prefabs, testing them in game, seeing them work, and then checking them into source control. And what gets checked in is an empty prefab, because while the prefab files got created, nothing actually gets saved into them unless you save the scene (and as they didn't change the scene itself, they don't think of saving it). It's gotten to where I'm routinely telling them to close Unity before checking anything in, because that guarantees everything gets saved.

So a solution would be one of two things - a Save-All-Changes button in the toolbar (disk icon), which is something people are used-to pressing all the time, or auto-saving changes anytime Play is pressed, which is something standard development environments like XCode or Visual Studio do.