Better sliders!

Add marks and value indication. (Fixes #146)

src/config/flowtypes.js

@@ -58,9 +58,10 @@ export type UISlider = $ReadOnly<{|
   topic: string,
   icon?: Icon,
   enableCondition?: (s: State) => boolean,
+  marks?: boolean | Array<{ value: number, label: string}>,
   min?: number,
   max?: number,
-  step?: number
+  step?: ?number
 |}>;
 
 export type UISection = $ReadOnly<{|

src/config/types.js

@@ -15,7 +15,7 @@ export const json = (path: string, innerType?: TopicType): TopicType => {
     from: (msg) => parseAgain(Buffer.from(
       at(JSON.parse(msg.toString()), path)[0].toString())),
     to: (msg) => Buffer.from(
-      JSON.serialize(set({}, path, parseFirst(msg).toString())))
+      JSON.stringify(set({}, path, parseFirst(msg).toString())))
   };
 };