[petsc-dev] Recover SNES ex6.c?

[Karl Rupp]

>     ex6.c had the additional hodge podge of extra stuff (...)
>    but it does the same model problem as ex2.c so I decided to nuke it.
>
>      I added the matrix free preconditioner as a shell matrix to ex3.c    I didn't see the other extra stuff worth saving. I will edit the users manual to take into account these changes. Thanks for noting the problem.

Adapting the documentation suitably is the cleanest option in the long 
run then. Thanks!

Best regards,
Karli