tc-install-GUI cann't determine "coreplus" in CorePure64

[yy1984]

https://github.com/tinycorelinux/fltk_projects/blob/master/tc-install/tc-install.cxx
string command = "grep 'Core Plus' dirname " + path + "/isolinux/isolinux.cfg >/dev/null 2>&1";
Line 129 uses the keyword 'Core Plus' to determine the path, but it cannot be found in the CorePure64 file isolinux.cfg.