Map shift/F1.. to F13..
The shft/F1 to shift/F12 keys are by default mapped to the functions F13 to F24 for the IBM emulations.
If this options is turned off, the shift/F1 to shift/F10 keys are mapped to the fucnctions F10 to F20 and the alt/F1 to alt/F4 the are mapped
to the functions F21 to F24.
This option is only valid for Glink3270 and Glink5250.