Add CobaltDelegate and onUnhandled calls, clean pull-to-refresh & infinite scroll

- Add CobaltDelegate and its methods onUnhandled…
- Add setDelegate method (must be called by inherited classes),
- Rename « loadContentInWebView: FromFileNamed: atPath:
withRessourcesAtPath: » in
« loadPage: inWebView: »,
- add callback to sendEvent method,
- add onUnhandled… calls,
- Rename « sendSimpleAcquitment » in « sendACK »,
- Clean PTR & IS (NB: IS should not work?)