API Changes

 - Load data asynchronously
 - DataModel constructor now takes an object of data and schema instead of two separate parameters
 - Select operation now takes a json object for query instead of a function
 - GroupBy operation now takes an array of objects containing aggregation function and field name instead of an object in second parameter

Improvements
 - Improve performance of data operations using webassembly
 - Use web workers to load data
 - Improve data propagation performance
 - Dispose api is added which must be called when the datamodel is no longer used for freeing the memory

Merge branch 'release/v2.3.1'

API Changes

- Introduced field registry to register new type of fields
- Introduced data converter registry for registering new types of data converters like geojson,tsv,etc

Bug Fixes
- Fix temporal field domain method
- Fix propagation when row id is passed in identifiers
- Minor bug fixes

Bugs

- Fix issue in dsv string parser
- Various bug fixes

Improvements

- Ability to use multi-sorting while retaining the group order
- Improve data point iterator for date/time field

Bugs
- Fix sorting and propagation
- Various bug fixes

Improvements

 - Increased performance for select operator
 - Various bug fixes

Improvements

- Add APIs for derivation
- Validate field type and subtype in schema
- Add alias property for a field in schema

Bugs
- Fix derivation issue for sort API

Improvements

- Manage handling of null / undefined / not parseable data
- Improve field hierarchy and provides additional field APIs

Bugs
- General bug fixing

Various improvements

- Better handling of mutable and immutable actions

Bug fixes

Bugs
- Retifies firing of propagation funciton multiple time while DAG receives propagation puleses