milton libs update (includes pull request https://github.com/miltonio/milton2/pull/12 )
refactoring: renamed paste to pasteAsSibling
drag'n'drop with TransferHandler
removed unused imports
removed user input waiting
echo version to VERSION, copy ZIP to ganttproject-latest.zip
removed unused getMenuFont
implemented drag'n'drop interactions using GPTransferHandler and Highlighter
get logger by name
refactoring: GanttChartSelection to separate file
use GanttChartSelection to create ClipboardContents
breadth first search with ability to filter nodes
added LinkedHashMultimap and required classes
remember task hierarchy in the clipboard and use it when pasting
fixes broken drag'n'drop and cut'n'paste for nested tasks