* Added a `clear' button to suppress style.
* Refactored some methods.
* Debugged the paste (only pastes content as cleaned text).
* Added multilines options
* Started to factor parameters.
* The input/output format can use span- or fragment- structure
  (fragment is default, span has to be specified in the
  parameters)
* Added a bundle folder with CSS.

TO DO: Debug the drag and drop, take the parameters out into
       richcontentparams.js