Make training API match JS
We've made some changes to the API in JS that are improvements and should be mirrored in JS.
- trainingData changes to trainingSet
- phrase changes to example
- the recording() methods are replaced by createExample() and addElement()
@MikeZ did a sketch of this that is now in the "next_api" branch: http://gitlab.doc.gold.ac.uk/rapid-mix/RAPID-MIX_API/tree/next_api
These two drafts need to be merged into one version on the next_api branch that is as close to the JS api we can make it.