pick a model interface prefix

[drewbanin]

currently it's @ which

• is groovy
• is not sql compliant

thusly, it appears a change is in order

[jthandy]

@drewbanin i'm not convinced of the need for a prefix like this. are there "fields" and then "special fields", only the latter of which get a symbol? I feel like this is just a symptom of us not really having figured out what interfaces look like. I'm kinda leaning towards closing this issue because it's really a part of that whole mess.