Merge operations

[Rich-Harris]

Ractive has a ractive.merge() operation which minimises the amount of DOM manipulation involved in updating list sections. It should be possible to use the same logic with Backbone collections.

[browniefed]

@Rich-Harris commenting on something from 3 months ago but any ideas on how to implement merge operations.
It seems that it would all be easier if the adaptors were providing with information about the Ractive operation (set/merge) that came about. As well as calling merge may have additional options compare: 'id' and such that you won't get passed along to the adaptor.

newData is an array of POJOs that should be converted to RowModels by Ractive
It also appears that if you call merge ractive.merge('rows', newData); it will set the whole new Collection on Ractive and provide you with the previousModels which now makes makes you have to do a reverse merge?

Other options would be never calling merge on the Ractive instance and define my own merge call that would operate at the Model level and reset models that it detects differently.