Add a way to further specify HeatmapEvents for aggregation

[Marc Tanenbaum]

This is a tricky topic, since "further specify" can mean a lot of things. A proposal has been floated to add an arbitrary string field "description" to the HeatmapEvent. Example use cases might be:

//Use description to specify on which level the event occurred.
HeatmapEvent.Send("PlayerDeath", transform.position, Time.time, "Level 1");

//Use description to specify a subtype of the main event
HeatmapEvent.Send("MagicPower", transform.position, Time.time, "SpellType:Heal");

//Use description to specify device aspect ratio
Vector2 touchPos = new Vector2(x, y);
HeatmapEvent.Send("UserTouch", touchPos, Time.time, "aspect16:9");

According to the proposal, the aggregator script would then be able to match a substring or regex to compute the categories.

[Marc Tanenbaum]

This work is now done and on a branch. You can group on an arbitrary parameter like "level" or "spell_type". Will bring to master when possible.

[Marc Tanenbaum]

Fixed on t2 branch