* Added image copy/paste operation from/to external application.
* IcyCanvas:
 - added roi copy/paste operation.
 - added roi copy_link/paste_link operation.
* Canvas2D: better support of getRenderedImage(...) image.
* Loader: new methods, lot of rewrite...
* added onClosed() method to ActionDialog.
* ImageLoaderDialog:
 - separated file choose and loading operation.
 - improved preview display.
* ImageSaverDialog: separated file choose and loading operation.
* added glow colormap.
* simplified Clipboard object.
* NetworkUtil: improved error handling.
* many fixes and improvements.
* some refactoring.