renamed node properties

For the benefit of both OO and non-OO node manipulation, I am going to add more node properties. As a result, I need to make some changes to some property names.

The current property list is

Txt            CHAR 

FirstChildNum  INT
NextSiblingNum INT
PrevSiblingNum INT
TypeNum        INT
IndexNum       INT
ParentNum      INT

FileNum        INT
LineNum        INT
ColumnNum      INT
RecordOffSet   INT

Type        CLASS NodeType 
FirstChild  CLASS node 
NextSibling CLASS node 
PrevSibling CLASS node 
Parent      CLASS node

as you can see, fields with "num" as a suffix are the actual node numbers themselves (with the exception of FileNum, LineNum and ColumnNum). So, FirstChildNum is the node number of the first child of a node, whereas FirstChild is the actual node object of the first child.