Add documentation link.

Split tests into folders.
Clean up unused (not implemented) API.

Add an example for this.
Gadget's ID is a mandatory argument so fix examples accordingly.

debugging.

wider scope outside Gadget itself).
Use concistent format for naming attributes.

Allow to control RenderJs's implicit gadget rendering process.
Make sure OfficeJs uses always recent RenderJs.

Follow same conventions for gadgets' root file.

Handle cases when for gadget_data_source and gadget_data_handler we have
empty strings.

loaded. Add simple test.

"data-" prefix.

RenderJS.

On Google Chrome or Chromium, requests methods (POST,PUT,GET,DELETE) act on the
internal browser cache, so important action like PUT could not work.
The Url sended with the request is appended by '?_=xxx' (which 'xxx' is the
current date in ms) to make this Url unique.