Implement CI for multiclass.roc

[xrobin]

CI is broken for multiclass.roc:

data(aSAH)
multiclass.roc(aSAH$gos6, aSAH$s100b, ci=TRUE)
Error in roc.default(response, predictor, levels = X, percent = percent,  : 
  formal argument "ci" matched by multiple actual arguments

It is also not possible to calculate a CI on an existing object:

ci(multiclass.roc(aSAH$gos6, aSAH$s100b))
Error in roc.default(response, predictor, ...) : No valid data provided.

This should work easily for univariate multiclass.roc. The new mv.multiclass.roc might need a bit more work.

[xrobin]

CI has really never been implemented for multiclass.roc. Dead code disabled and cleaner error messages implemented until it is available.

[snagaraj0]

Is this available yet?

[xrobin]

@snagaraj0 This is pretty low in my priority list. I'm unlikely to have time to implement it any time soon, but I always welcome pull requests. Let me know if you'd like to contribute!