tunnel to not pro-actively close down when failing an SSL handshake.

* Change the cert-chain callback - originally this was the same one used in
  s_client and s_server but the output's as ugly as sin, so I've prettied
  tunala's copy output up a bit (and made the output level configurable).

* Remove the superfluous "errors" from the SSL state callback - these are just
  non-blocking side-effects.

exists in bn_sqrt.c now

test_bn still fails in the BN_sqrt test because
small primes appear to turn into zero for no
obvious reason, leading to "div by zero" errors.

are not reduced modulo m, the outputs won't be either).

similarly modified now on DH and DSA.

the initialisation and cleanup of "ex_data" elements to before an init()
handler and after a finish() handler respectively.

(we need the two's complement of BN_lsw then).

* A little bit of code-cleanup
* Reformat the usage string (not so wide)
* Allow adding an alternative (usually DSA) cert/key pair (a la s_server)
* Allow control over cert-chain verify depth

so we have to reduce the random numbers used in test_mont.

Before this change, test_mont failed in [debug-]solaris-sparcv9-gcc
configurations ("Montgomery multiplication test failed!" because
the multiplication result obtained with Montgomery multiplication
differed from the result obtained by BN_mod_mul).
Substituing the old version of bn_gcd.c (BN_mod_inverse) did not avoid
the problem.

The strange thing is that it I did not observe any problems
when using debug-solaris-sparcv8-gcc and solaris-sparcv9-cc,
as well as when compiling OpenSSL 0.9.6 in the solaric-sparcv9-gcc
configuration on the same system.

For the server side this was already done one year ago :-(

Improve readability of bn_shift.c.

Add comment in bn_lib.c (why zero data between top and max?)

Change bntest.c output for BN_kronecker test

I'm still investigating what caused the segementation fault
(maybe "make clean; make" will cure it ...).
But BN_bin2bn should always reset ret->neg.

This caused a segmentation fault in calls to malloc, so I cleaned up
bn_lib.c a little so that it is easier to see what is going on.
The bug turned out to be an off-by-one error in BN_bin2bn.

Modify "CHANGES" entry for BN_mod_inverse (it's not just avoiding BN_div
that increases performance, avoiding BN_mul also helps)

Get the BN_mod_exp_mont bugfix (for handling negative inputs) correct
this time.

bn_add_words(), not bn_sub_words()...

command line, and make the peer-authentication similarly configurable.

- Add "-cipher" and "-out_state" command line arguments to control SSL
  cipher-suites and handshake debug output respectively.

- Implemented error handling for SSL handshakes that break down. This uses
  a cheat - storing a non-NULL pointer as "app_data" in the SSL structure
  when the SSL should be killed.

or two kinks lurking around, but it now appears to deal with the basic
test cases ok.

Sketch the test for BN_kronecker.

Also add the next file in advance so that I can't forget this one :-)