Changes from V3

• Enables accordion expansion either upwards or downwards
• Added animated caret for upward accordions

Example

view : Model -> Html Msg
view model =
    div []
        [ Accordion.view
            { entries =
                [ AccordionEntry
                    { caret = Accordion.updwardCaret
                    , content = \() -> text "Accordion Content"
                    , entryClass = "a-class-distinguishing-this-accordion-from-others-on-the-page"
                    , expansionDirection = Accordion.Upwards
                    , headerContent = text "Accordion Header"
                    , headerId = "a-unique-id-for-this-accordion-header-button"
                    , headerLevel = Accordion.H1
                    , isExpanded = model.isAccordionOpen
                    , toggle = Just ToggleAccordion
                    }
                    []
                ]
            , focus = Focus
            }
        , Accordion.styleAccordion
            { entryStyles = []
            , entryExpandedStyles = []
            , entryClosedStyles = []
            , headerStyles = []
            , headerExpandedStyles = []
            , headerClosedStyles = []
            , contentStyles = []
            }
        ]