Conf matrix and ROCMeasures

[ja-thomas]

Documentation for two new functions in mlr calculateROCMeasures and calculateConfusionMatrix.

Do not merge this before PR #1113 and #1071 in mlr are merged.

Feedback appreciated :)

[ja-thomas]

Both above mentioned PRs are now merged. Should hopefully be ready to merge after travis passes and somebody has proofread it.

Thanks

[schiffner]

Will do, thx!

[schiffner]

Sorry for taking this long and thank you for writing this!

I went into your branch, did a little cleanup and tweaked the language a little.
The only small addition I made is to show how to get the relative values normalized in one direction from the ConfusionMatrix object (i.e. $relative.col and $relative.row, because that's something that I would want to know and use).
Ok?

The link from the performance page to the confusion matrix section was broken. How to do this correctly is not explained very clearly in the mkdocs documentation. I added a short explanation to the tutorial README, so in the future we know...

[ja-thomas]

perfect, thanks :)

[schiffner]

Ok, merging. And also thanks :)