v3.2.0

• Allow driverless type definitions #953
• Change Elastica constraints to allow ~2.1 as Elastica now follows semver
• Add support for the dynamic setting in mapping
• Fixed PropelCollection to array casting error #992
• Allow set retryOnConflict per connection
• New event PRE_TRANSFORM which allows developers to modify objects before
  transformation into documents for indexing
• Introduce serialize_null option for Serializer
• Ability to specify custom connection settings for functional tests
• Doctrine: possible to use hints when hydrating objects
• Resolved Propel configuration
• Add Elastica compression option
• Add support for defaultSortFieldName and defaultSortDirection pagination options
• Removed immediate option on type persistence configuration
• Enable pagination of hybrid results
• Add Symfony Serializer support