ADDGROUP - (C) Copyright Glenn B. Lawler, 1994. All Rights Reserved.
Where GroupFileName is the name of a windows group file to be
added to program manager. Extension defaults to .GRP.
Windows must be running for this program to function.
ERRORLEVEL is set to 1 if an error is encountered Loading or
Saving PROGMAN.INI. ERRORLEVEL is set to 2 if GroupFileName
is already in PROGMAN.INI. If GroupFileName is not found, a
warning message is displayed, but processing continues.