Add Entity Audit diff to support revision comparison
Fix formatting issues
Fix wrong history table heading label
Merge remote-tracking branch 'upstream/master' into add_entity_audit_compare
Added diff method to AuditReaderInterface
Undo add AuditReader diff method
Change the compare action to re-use the existing show action for comparison
Change css .diff class scope
Fix unit tests
Added code improvements (eko comments)
Added test for ErrorElement
Merge pull request #2291 from pulzarraider/error_element_test

Added test for ErrorElement
Merge master - resolve Resources/doc/reference/templates.rst by using theirs
Reset templates.rst templates alignment (was merge conflict)
Updated ModelToIdPropertyTransformer so it works with Entities which implement \ArrayAccess
Added FooArrayAccess class to allow testing of new code
See #2301
Fixed code value in sonata_type_model_autocomplete_widget so it works with embedded admins
Fixed $property name in HelperController::retrieveAutocompleteItemsAction() (was $prop)
- minor change to exception message so apostrophe is not needed
- removed unused Controller reference from top of HelperController
Wrong variable name
Merge pull request #2306 from Alekc/patch-1

Wrong variable name
Updated logic and added Exception messages when an incorrect configuration is used.
Merge pull request #2266 from nlzet/add_entity_audit_compare

Add Entity Audit diff to support revision comparison