Freehand mode drawing experience could be smoother

[JamesLMilner]

Original issue for this is #2 (thank you again @dabreegster!) , I am extracting this so it can be tackled in isolation.

The problem here is that the Freehand drawing tool currently uses a rate limiting/throttling mechanism against the incoming events, to prevent too many points being created and hence a large amount of data. However, as pointed out this can lead to a bit of a choppy experience whilst drawing. The solutions here are to potentially decrease the aggressiveness of the throttling via the reducing the everyNthMouseEvent default property, or to take a different approach such as a minimum distance threshold (probably best to implement in pixel distance). The pixel distance approach would probably be the smoother of the two approaches but it would be good to experiment. There may also be other approaches, or a combination which result in better results with regards to the smoothness/data size tradeoff.

[JamesLMilner]

Resolved in 0.0.1-alpha.9. You can now use the minDistance property that defaults to 20 pixels.