OSLib os.h clash with CathLibCPP

[Jonathan Coxhead]

   Let me try out this spiffy new mailing list. Here's an old 
question of John's I forgot to reply to ...

 | Why not use enum's ?

   Because they are (or can be) distributed across different headers
---we want to be able to define "message" values in different files, 
for example, and "Wimp.swi" defines |Wimp_NoFonts|, and so on.

   You might think that in C++ you could write

      enum fred {A, B, C};

      enum jane: fred {D, E};

to get a subtype |jane| of |fred| that could take values |A|, |B|, 
|C|, |D|, |E|; but that isn't the case. If it were, it would be 
exactly what was needed to allow different modules to contribute 
values to an enumerated type.

   It also keeps DefMod simpler---always a good thing.

        /|
 o o o (_|/
        /|
       (_/