Give SNES objects names. This is useful for passing options on the
command line to specific solves.
Add an options_prefix to TAO.

I can't test this, because the latest publicly available TAO doesn't
compile against petsc-dev. I've submitted a bug report to TAO.
More options_prefixes for PETSc objects.
Merge branch 'pefarrell/give-snes-solvers-names'