EZP-21036: introduce fieldtype Value interface
EZP-21036: adapt for Value interface and refactor acceptValue()
EZP-21036: refactored fieldtype: Author
EZP-21036: refactored fieldtype: BinaryBase
EZP-21036: refactored fieldtype: BinaryFile
EZP-21036: refactored fieldtype: Media
EZP-21036: refactored fieldtype: Checkbox
EZP-21036: refactored fieldtype: Country
EZP-21036: refactored fieldtype: Date
EZP-21036: refactored fieldtype: DateAndTime
EZP-21036: refactored fieldtype: EmailAddress
EZP-21036: refactored fieldtype: Float
Fixed: enable storing empty value
EZP-21036: refactored fieldtype: Image
EZP-21036: refactored fieldtype: Integer
EZP-21036: refactored fieldtype: Keyword

- fixed accepting string input value
EZP-21036: refactored fieldtype: MapLocation
EZP-21036: refactored fieldtype: Null
EZP-21036: refactored fieldtype: Page
EZP-21036: refactored fieldtype: Rating