This is a utility function to create a 'graph' data structure to pass to chart module
df2g(title, dxy, ndim = 1, nseries = 1)
is the title for the chart
is the dataframe to draw the chart from
is the number of dimensions in the xl file; it is assumed these are in the first ndim columns of the xl
is the number of series in the xl file; it is assumed these are in the last nseries columns of the xl