Create rough app outline

Multiplatform/Shared/SceneNavigationView.swift

@@ -0,0 +1,39 @@
+//
+//  SceneNavigationView.swift
+//  NetNewsWire
+//
+//  Created by Maurice Parker on 6/28/20.
+//  Copyright © 2020 Ranchero Software. All rights reserved.
+//
+
+import SwiftUI
+
+struct SceneNavigationView: View {
+    var body: some View {
+		NavigationView {
+			#if os(macOS)
+			SidebarView().frame(minWidth: 100, idealWidth: 150, maxWidth: 200, maxHeight: .infinity)
+			#else
+			SidebarView()
+			#endif
+
+			Text("Timeline")
+				.frame(maxWidth: .infinity, maxHeight: .infinity)
+
+			#if os(macOS)
+			Text("None Selected")
+				.frame(maxWidth: .infinity, maxHeight: .infinity)
+				.toolbar { Spacer() }
+			#else
+			Text("None Selected")
+				.frame(maxWidth: .infinity, maxHeight: .infinity)
+			#endif
+		}
+	}
+}
+
+struct NavigationView_Previews: PreviewProvider {
+    static var previews: some View {
+        SceneNavigationView()
+    }
+}