Thanks Tom-This thread moves along quickly -I missed this
Believe it or not I woke up this am with the same thought -to rename all "C" files to ".cpp" and see what happened on starting Arduino IDE
I had not even considered the "extern C" though
I D/L your changed files removed the ones I had in the library and fired up the IDE and program again with no change in the result unfortunately.
I will however keep studying it . It does not give an error message on start of the IDE so I am assuming it is compiling something - just have to find out what.