Initial modifications for XML-based sheet readers to use XMLReader via streaming for large files in the listWorksheetNames() and listWorksheetInfo() methods... still needs some additional work for merged cells to work correctly, but gives a hell of a memory boost and executes more quickly - the same principles will be applied to the core data readers, but that still requires a lot more work. However, when completed, the effort should be worth it for both speed and memory usage, and the code should be a lot cleaner for the core data reader as well