Some fixes, hello-world example (not working)

Finding it hard to debug on Windows at least (the compiler's threads
seem to be garbling each others output).

One error I got from the C compiler:

c/mingw32/4.7.2/../../../../include/iup/iup.h:13:20: fatal error:
iupkey.h: No such file or directory

Maybe it needs an IncludePaths directive in the .use file?