In-line editing should work with the raw property value not the display value

ATM if you double click on a cell that uses the HTML displayer you end up editing the HTML code. This is not right. A property that uses the HTML displayer and that is editable must have a raw property value. For live tables we have this naming convention:

{
  ...
  "someProperty": "display value (could be HTML)",
  "someProperty_value": "raw property value",
  ...
}

We also need to figure out how to integrate the property (edit) displayers that are available on the server side. This means that the live data HTML displayer should:

• when entering edit mode: try to load the actual edit displayer from the server
• when leaving edit mode: call the displayer from the server (the one that produced the initial HTML we got as property value)