Added undo manager constructor parameter
Fixed NPE occurring if the there is no commandUIFactory (e.g. in NetBeans)
Format to Java 8
Removed outdated TODOs
FigureEditor now exposes it's UndoContext
Rewording of undo name and removed outdated TODO
Removed outdated TODOs
Added undo/redo for figure insertions/removals
Added undo/redo for figure changes (--> correctly implemented the memento pattern)
added KeyStoreProvider to validate signed plugins

added keystore file
added s3tbx Update Center
EMPTY.clone() must return EMPTY
Implemented setSelection(), removed TODO
Avoided possible NPE
Fixed: setSelection(Selection selection);
added clone() method in order to implement paste() correctly