Hi,
Sorry to tell you that I have made a mistake that I have put the files,TFT.cpp,TFT.h,TouchScreen.cpp,TouchScreen.h,in the folder of touchscreendemo.
I guess that you have compiled the touchscreendemo.ino so you can delete all the files in the folder of touchscreendemo but not touchscreendemo.ino.And then restart the IDE.It will be ok.
Regards,
Frankie