[Foxtrot] New abstract classes

[Alan Lawrence]

Hi All,

I've made some changes to the abstract class definitions, and
correspondingly to all the stuff in the src tree, for RMI. 'Server' is now
'ServerImpl', and lives entirely on the server computer; the new 'Server'
is just an interface for the client to use - presumably, an RMI
proxy. I've updated abstract_classes.txt but not abstract_classes.tex .
Also, since the version we printed out for Dr Anderson, we altered
SuccessfulResult to only store two factors, rather than an arbitrary
number, since it makes it simpler and it's unlikely we'll ever find lots
of factors at once.

Progress-wise, I've now (I hope) done all the back-end stuff, just the UIs
to do.

Time-wise: 3hrs on friday, 3hrs on saturday.

Cheers,

Alan