Warning for unsupported hardware

[ikorb]

It would be nice if the menu system would use the information in the rom header to figure out if the selected file has a chance of running on sd2snes or if it (seems to) require coprocessors that are not implemented yet. In the latter case it should display a warning message, giving the user a chance to run the file anyway in case the header is wrong or the user has some reason to try anyway.