Files[] array going now ...

[Andrew Tridgell]

Carrying on my rampage though the code, I am currently removing the
fnum references and the global Files[] array and using files_struct*
instead. 

I know Richard was going to do this, but I figure that my massacre of
the code yesterday almost certainly destroyed any work he was doing so
to make up for it I thought I'd do it myself. I should be able to do
it faily quickly as I developed some techniques and tricks while doing
the cnum conversion that allow this stuff to do done more quickly.

watch out for another large checkin later this afternoon.