[WIP] Feature predictionenhance

[willwade]

• Adds sentence history collection. Im not sure about collecting each utterance. I think we need to scrap that but I've left it in for thoughts
• (Related Save favourites (frequent) phrases and list them #301 but not in this PR)
• For Sentence Prediction #422

Definitely needs reviewing this and thinking about. I think a good load of work could be done to overhaul prediction API to use something more offline.. (NB: If putting into a cordova like wrapper you would just use system prediction API's.. but otherwise look at PPM or others that have been compiled to wasm)

[willwade]

@klues - look at this BEFORE looking at #579 etc - as I think if we accept this one it will conflict with that and I'll rework them

[willwade]

Note to myself @willwade - come back to this after all other symbol prediction etc work done. There is a bit of a crossover in places here