Tidy app

Now that I have a deployed an MVP of my app, I am tidying things up to support
the next phase of development.

TL;DR:
- Moved application Model-related code into State module
- Moved each View into its own module
- Deleted unused ChordInspector component
- Deleted unused Msg's, {Increase,Decrease}Tempo
- Deleted misc unused code

website/sandbox/learnpianochords/src/Practice.elm

@@ -0,0 +1,44 @@
+module Practice exposing (render)
+
+import Html exposing (..)
+import Html.Attributes exposing (..)
+import Html.Events exposing (..)
+import Icon
+import Piano
+import State
+import Theory
+import UI
+
+
+openPreferences : Html State.Msg
+openPreferences =
+    button
+        [ class "w-48 h-48 absolute left-0 top-0 z-40"
+        , onClick (State.SetView State.Preferences)
+        ]
+        [ Icon.cog ]
+
+
+render : State.Model -> Html State.Msg
+render model =
+    let
+        ( handleClick, buttonText ) =
+            if model.isPaused then
+                ( State.Play, "Press to practice" )
+
+            else
+                ( State.Pause, "" )
+    in
+    div []
+        [ openPreferences
+        , UI.overlayButton
+            { label = buttonText
+            , handleClick = handleClick
+            , isVisible = model.isPaused
+            }
+        , Piano.render
+            { highlight = model.selectedChord |> Maybe.andThen Theory.notesForChord |> Maybe.withDefault []
+            , start = model.firstNote
+            , end = model.lastNote
+            }
+        ]