Added three oc functions:

1. int GraphPage::CanDuplicate(int nWith = CAN_DUP_WITH_ANY);
Suppose a graph is active, use this OC function to tell if this graph is possible to duplicate with new columns, sheets, books.

2. int GetDuplicateWithCols(StringArray &saItems, DataPlot &dataPlot = NULL, int nModifier = PMMT_IGNORE);
Assume a graph is active, use this OC function to get the list of columns which can be used to batch plot the graph.

3. int GetDuplicateWithBooks(StringArray &saItems, int nModifier = PMMT_OFFSET, int nMatchCol = MATCHCOLUMN_INDEX, int nMatchSheet = MATCHSHEET_INDEX);
Assume a graph is active, use this OC function to get the list of sheets or books which can be used to batch plot the graph. If nMatchSheet == MATCHSHEET_IGNORE then Range is Sheet, else Range is Book.