build: fix compiler and cmake warnings

added missing virtual destructor
fixed a warning in token.h: expression with side effects will be evaluated despite being used as an operand to 'typeid'
CMP00043 Cmake warning
added missing override keyword

src/lib/component/view/GraphViewStyleImpl.h

@@ -6,6 +6,7 @@
 class GraphViewStyleImpl
 {
 public:
+	virtual ~GraphViewStyleImpl() { }
 	virtual float getCharWidthForNodeType(Node::NodeType type) = 0;
 	virtual float getCharHeightForNodeType(Node::NodeType type) = 0;
 };