Prepare 4.1.0

Prepare 4.0.1 release

Release 4.0

Merge pull request #60 from marmelab/document-operators

Document operators

Prepare changelof for 3.4

Prepare v3.2.0

Merge pull request #38 from marmelab/support-filter-deep-objects

Add support for object filtering

prepare 3.1.0

Merge pull request #35 from marmelab/modernize-tests

Modernize test