Fully Deprecate "projects in URLs" setting

[cycomachead]

We no longer leave this on, and it's a shift-click setting.

So, I think it's time to yank this code. There's two reasons for this:

• IDE_Morph#setURL is kind of confusing as function. It only works when the setting is on.
• when you export a project, we call setURL but that means if you have a project opened from the cloud, the URL disappears, so I think that behavior is wrong.
• The only other place this is used is when opening a project from localStorage. I think we'd be better off my using a tag #local:projectName if we wanted to be able to easily load the project again, but mostly I don't think this is necessary.
• Now that all cloud projects update the URL, you can do development just by reloading from the cloud, even with private projects used for testing.

ok, that's more than two. :)