Monorepo structure, remove Gulp, new build process (#2116)

preview/pages/_data/layouts.json

@@ -0,0 +1,78 @@
+[
+  {
+    "title": "Default tabler layout",
+    "page": "layouts.html",
+    "config": {
+      "topmenu": true
+    }
+  },
+  {
+    "title": "Dark navigation",
+    "page": "layout-dark-navigation.html",
+    "config": {
+      "topmenu": true,
+      "topmenu-dark": true
+    }
+  },
+  {
+    "title": "Dark topnav",
+    "page": "layout-dark-topnav.html",
+    "config": {
+      "topmenu": true,
+      "topnav-dark": true
+    }
+  },
+  {
+    "title": "Sidebar",
+    "page": "layout-sidebar.html",
+    "new": true,
+    "config": {
+      "sidebar": true
+    }
+  },
+  {
+    "title": "Dark sidebar",
+    "page": "layout-sidebar-dark.html",
+    "new": true,
+    "config": {
+      "sidebar": true,
+      "sidebar-dark": true
+    }
+  },
+  {
+    "title": "Narrow sidebar",
+    "page": "layout-sidebar-narrow.html",
+    "new": true,
+    "config": {
+      "sidebar": true,
+      "sidebar-narrow": true,
+      "sidebar-dark": true
+    }
+  },
+  {
+    "title": "Right sidebar",
+    "page": "layout-sidebar-right.html",
+    "new": true,
+    "config": {
+      "sidebar-right": true
+    }
+  },
+  {
+    "title": "Sidebar only",
+    "page": "layout-sidebar-only.html",
+    "new": true,
+    "config": {
+      "sidebar": true,
+      "hide-topnav": true
+    }
+  },
+  {
+    "title": "Dark mode",
+    "page": "layout-dark.html",
+    "soon": true,
+    "config": {
+      "sidebar": true,
+      "sidebar-dark": true
+    }
+  }
+]