First major change to PDTE

The script now shows info for all programs, not just SNAP. The dialog
has been modified, and a new custom function included for
"convert_digit_to_excel_column", which converts a number to a letter for
Excel purposes. This will likely prove helpful enough to be included in
FUNCTIONS FILE.

Script now also allows multiple workers to be entered into the worker
editbox, separated by a comma (script splits them by comma).

Additional comments in code. More changes to come today. Stay tuned.