Continued working on scanner.

We're now using exceptions for errors, and scanning/pushing tokens is exception-safe (using a set of "limbo tokens").

token.h

@@ -3,8 +3,25 @@
 namespace YAML
 {
 	class Token {};
+
 	class StreamStartToken: public Token {};
 	class StreamEndToken: public Token {};
 	class DocumentStartToken: public Token {};
 	class DocumentEndToken: public Token {};
+
+	class BlockSeqStartToken: public Token {};
+	class BlockMapStartToken: public Token {};
+	class BlockEndToken: public Token {};
+	class BlockEntryToken: public Token {};
+
+	class FlowSeqStartToken: public Token {};
+	class FlowMapStartToken: public Token {};
+	class FlowSeqEndToken: public Token {};
+	class FlowMapEndToken: public Token {};
+	class FlowEntryToken: public Token {};
+
+	class KeyToken: public Token {};
+	class ValueToken: public Token {};
+
+	class PlainScalarToken: public Token {};
 }