[Clp] Major changes to trunk for Cbc and Clp

[John J Forrest]

To all users of Cbc/trunk and Clp/trunk.

I will be committing a large number of changes to Cbc and some to Clp in
the near future.  I have tried to test the changes and overall they should
improve performance and stability, but I expect I will cause some problems
for a few users.

I would therefore suggest that people who might be affected update their
version of trunk before the weekend and keep that version around.

John Forrest