First version of new ui based on tailwind

This drops fomantic-ui as css toolkit and introduces tailwindcss. With
tailwind there are no predefined components, but it's very easy to
create those. So customizing the look&feel is much simpler, most of
the time no additional css is needed.

This requires a complete rewrite of the markup + styles. Luckily all
logic can be kept as is. The now old ui is not removed, it is still
available by using a request header `Docspell-Ui` with a value of `1`
for the old ui and `2` for the new ui.

Another addition is "dev mode", where docspell serves assets with a
no-cache header, to disable browser caching. This makes developing a
lot easier.

modules/webapp/src/main/elm/Comp/MarkdownInput.elm

@@ -5,16 +5,22 @@ module Comp.MarkdownInput exposing
     , update
     , view
     , viewCheatLink
+    , viewCheatLink2
     , viewContent
+    , viewContent2
     , viewEditLink
+    , viewEditLink2
     , viewPreviewLink
+    , viewPreviewLink2
     , viewSplitLink
+    , viewSplitLink2
     )
 
 import Html exposing (..)
 import Html.Attributes exposing (..)
 import Html.Events exposing (onClick, onInput)
 import Markdown
+import Styles as S
 
 
 type Display
@@ -51,6 +57,10 @@ update txt msg model =
             ( { model | display = dsp }, txt )
 
 
+
+--- View
+
+
 viewContent : String -> Model -> Html Msg
 viewContent txt model =
     case model.display of
@@ -172,3 +182,94 @@ splitDisplay txt =
                 ]
             ]
         ]
+
+
+
+--- View2
+
+
+viewContent2 : String -> Model -> Html Msg
+viewContent2 txt model =
+    case model.display of
+        Edit ->
+            editDisplay2 txt
+
+        Preview ->
+            previewDisplay2 txt
+
+        Split ->
+            splitDisplay2 txt
+
+
+viewEditLink2 : (Bool -> Attribute Msg) -> Model -> Html Msg
+viewEditLink2 classes model =
+    a
+        [ onClick (SetDisplay Edit)
+        , classes (model.display == Edit)
+        , href "#"
+        ]
+        [ text "Edit"
+        ]
+
+
+viewPreviewLink2 : (Bool -> Attribute Msg) -> Model -> Html Msg
+viewPreviewLink2 classes model =
+    a
+        [ onClick (SetDisplay Preview)
+        , classes (model.display == Preview)
+        , href "#"
+        ]
+        [ text "Preview"
+        ]
+
+
+viewSplitLink2 : (Bool -> Attribute Msg) -> Model -> Html Msg
+viewSplitLink2 classes model =
+    a
+        [ onClick (SetDisplay Split)
+        , classes (model.display == Split)
+        , href "#"
+        ]
+        [ text "Split"
+        ]
+
+
+viewCheatLink2 : String -> Model -> Html msg
+viewCheatLink2 classes model =
+    a
+        [ class classes
+        , target "_new"
+        , href model.cheatSheetUrl
+        ]
+        [ i [ class "fa fa-question mr-2" ] []
+        , text "Supports Markdown"
+        ]
+
+
+editDisplay2 : String -> Html Msg
+editDisplay2 txt =
+    textarea
+        [ class S.textAreaInput
+        , class "h-full"
+        , onInput SetText
+        , placeholder "Add notes here…"
+        , value txt
+        ]
+        []
+
+
+previewDisplay2 : String -> Html Msg
+previewDisplay2 txt =
+    Markdown.toHtml [ class "markdown-preview" ] txt
+
+
+splitDisplay2 : String -> Html Msg
+splitDisplay2 txt =
+    div [ class "flex flex-row justify-evenly" ]
+        [ div [ class "w-1/2" ]
+            [ editDisplay2 txt
+            ]
+        , div [ class "w-1/2" ]
+            [ previewDisplay2 txt
+            ]
+        ]