Refactor COUNT to use new aggregation framework
Refactor approximate count to use new framework
Add support for decomposable aggregation in new framework
Migrate learn_libsvm_regressor to new framework
Migrate learn_libsvm_classifier to new framework
Migrate learn_classifier to new framework
Migrate learn_regressor to new framework
Remove InternalAggregationFunction interface
Change scalar ML functions to take map
Add more tests to ML plugin