TSAGE: Fix bug #6545 "Ringworld2 - F5 doesn't create a save game the first time"

The save dialog glitched es the F5 event was already processed in
engines/tsage/core.cpp and it caused the to immediately reopen.
Merge pull request #449 from gazben/bug6545Fix

TSAGE: Fix bug #6545 "Ringworld2 - F5 doesn't create a save game the first time"