Modified revamp of the libsmbclient interface.

[Derrell Lipman]

I expect this will be much more acceptable to folks.  Here's the
commit message from my recent checkin,
which to repeat, can be viewed at us2:/data/git/derrell/samba3 ...
I've tested this version with konqueror to ensure ABI compatibility.
Please comment.  Following a bit more testing, I'm ready to check this
into 3.2-test for inclusion in the release.

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Given the tacit (if that) approval by some people, and clear disapproval by
others for my proposed clean-up and reorganization of libsmbclient, I've come
up with a slightly different approach.  This commit changes back to the
original libsmbclient.h SMBCCTX structure which will maintain ABI
compatibility.  I retain, here, the setter and getter functions which all new
code should use.  Older programs already compiled should continue to work
fine.  Older programs being recompiled will encounter compile-time errors
(intentionally!) so that the code can be corrected to use the setter/getter
interfaces.

Although this doesn't clean up the interface in the way I had wanted, the code
reorganization and requirement for new programs to use the setters and getters
allows future progress to be made on libsmbclient without further muddying up
the interface, while retaining the ABI compatibility that was the big issue
causing disapproval.  I hope that this compromise is adequate.

Derrell