AnnotationSet optimisations.

addSet:
* Instead of indexing items in the store, just union the indexStore arrays

removeSet/removeNotInSet:
* difference or intersect the indexStore arrays

filter:
* push indices into the result set instead of values

simpleArrayUnion/Intersect/Difference have been created as utilities
in ve. They are prefixed 'simple' because they use object keys to
do fast in-array comparisons. This means they are limited to string
values or values which will compare as strings (e.g. numbers).

Change-Id: I079cbdfece4f6d80ec0afd61959913f13217fcb3
Merge "AnnotationSet optimisations."