* GUI:
 - now preserve last file filter used on load image dialog.
 - fixed multiple plugin launch from Ribbon plugin button.
* ROI:
 - fixed point removing on polygon.
 - now selected ROI keep their color (only border is modified).
 - removed 'selected color' property.
 - added 'opacity' property.
* ImageJ wrapper: TRACED_ROI (ImageJ) are now converted to ROI2DArea.