Comment 19 for bug 1171276

We can keep the old syntax for existing snippets - updating is then a little more work.

I am not a huge fan of alias, because it seems to be more useful after the fact - i.e. if a shipped snippet has a weird trigger you want to define an alias that just defers to it. But I think this could be easily solved by allowing a snippet to reference other snippets (i.e. explicitly chain snippets.).