Subheader Pointer Format for referencing different pages not handled.

In working on another Pull request, I came across a sas7bdat file that contains subheaders that produced I/O Exceptions. Opening the file up with a binary viewer, it was very obvious that the Subheader Pointer Offset was not a decimal pointer to an offset inside the page, but was a Decimal Pointer to the page number that the record persists in.

So, there is some restructuring that the subheader pointers need. They need to be able to function in their current way, but then also need to handle the possibility of referencing other pages.

This is most likely due to the associated indexes in the SAS file, making reading/editing the binary file easier and more efficient.

I currently cannot recreate a test sas7bdat file with this associated issue, as I am unaware of how to recreate the scenario. I can keep trying in the coming weeks.