interpolating view methods with args

[ianstormtaylor]

in a simple view like this:

<input name="username" value="{ query('username') }">

where the view has a helper like this:

View.prototype.query = function (key) {
  var query = querystring.parse(location.search);
  return query[key];
};

i'd expect that interpolation to work, but because of this line it seems like its only checking the model for function calls inside interpolation. is this a feature or just view support hasnt been added yet? i can hopefully add it if so

[tj]

I forget where I left off with that stuff haha I know it's inconsistent right now with how interp and non-interp stuff is handled but that should definitely work

[defunctzombie]

This would be great to have especially now that I removed formatters for reactive 1.0 tho still trying to come up with a good example usecase for this that isn't already handled

[defunctzombie]

Duplicate of #76