prettier config + format all, closes #175

.prettierrc

@@ -0,0 +1,16 @@
+{
+	"useTabs": false,
+	"tabWidth": 4,
+	"singleQuote": true,
+	"trailingComma": "es5",
+	"printWidth": 100,
+	"overrides": [
+    {
+      "files": "**/*.svelte",
+      "options": {
+        "plugins": ["prettier-plugin-svelte"],
+		"parser": "svelte"
+      }
+    }
+  ]
+}