1. made zoom functionality using plantuml.jar code (smooth)
2. added image zooming by mouse (ctrl+mouse wheel)
3. added image scrolling by mouse (mouse wheel)
4. added image dragging by mouse
5. changed toolwindow background color to white
6. copy-to-clipboard action now uses current zoom
zoom has to be positive
Merge branch 'hza-smooth_zooming'
Merge branch 'master' of https://github.com/esteinberg/plantuml4idea into allPages2

Conflicts:
	src/org/plantuml/idea/action/CopyDiagramToClipboardAction.java
	src/org/plantuml/idea/plantuml/PlantUml.java
	src/org/plantuml/idea/toolwindow/PlantUmlToolWindow.java