Enums for TapNoteType, TapNoteSubType, and TapNoteSource

I intend to make additional useful information available on judgments,
such as TapNoteType and TapNoteSubType( for hold judgments ).

I am submitting this part as a separate pull request because it is more
generally applicable to anything TapNote related.

src/NotesWriterJson.cpp

@@ -55,9 +55,9 @@ static void Serialize( const TapNote &o, Json::Value &root )
 {
 	root = Json::Value(Json::objectValue);
 
-	if( o.type != TapNote::tap )
+	if( o.type != TapNoteType_Tap )
 		root["Type"] = (int)o.type;
-	if( o.type == TapNote::hold_head )
+	if( o.type == TapNoteType_HoldHead )
 		root["SubType"] = (int)o.subType;
 	//root["Source"] = (int)source;
 	if( !o.sAttackModifiers.empty() )