Added IBAComplexFormField which depends from multiple key paths.
Added IBATextFormFieldWithAction - for creating text field as button.
Changed sample (added new fields).
In class IBAFormDataSource added method for inserting sections with animation.
In class IBADateInputProvider property datePicker made public.
Added formFieldWillBecomeActive and formFieldDidBecomeActive methods to IBAInputRequestorFormField delegate.
Added start value for IBASingleIndexTransformer.
Added IBATextAreaFormFieldCell - for creating text area field.