UBDownloadManaget was adapted to use UBAsyncLocalFileDpownloader and QNetrowrkRequest bouth.

Items duplication adapted to new ideology of adding media items on the board.

Have a problem - should take care about saving original src path.

Document navigator: "Add pages from file" isn't work with old UBZ

Show Desktop: "Erase all" button isn't work

Desktop mode is broken
SANKORE-633
Positioning of floating palettes inside layers .

Mouse events handlers works for UB types and for some Qt types. Mouse events for other items hanlded by QGraphicsView.
It solves some troubles with items selections and fixes Sankore-721.

Fixed some related issues.

TODO:
 * nice icon
 * nice brush
 * fix draw with marker

UBToolWidget.cpp/.h cleaned too.