refactor: use the delegate pattern for TreeCellEditor
refactor: use the delegate pattern for TreeCellEditor

mhcrnl/java-swing-tips,aoguren/java-swing-tips,aterai/java-swing-tips,aoguren/java-swing-tips,mhcrnl/java-swing-tips,aoguren/java-swing-tips,mhcrnl/java-swing-tips,aterai/java-swing-tips,aterai/java-swing-tips,aterai/java-swing-tips