merge petscsnesfas.h into petscsnes.h
Merge branch 'barry/rm-petscsnesfas_h' into next
removed PCASA and supporting DMADDA
they don't work and if needed need to be rewritten
Merge branch 'barry/rm-pcasa' into next

Conflicts:
	src/dm/impls/makefile
	src/ksp/ksp/examples/tutorials/ex38.c
	src/ksp/ksp/examples/tutorials/ex39.c
	src/ksp/pc/impls/makefile
PetscMalloc: allow ptr=malloc(0) and free(ptr)

  ISO C90 §7.10.3: "If the size of the space requested is zero, the
  behavior is implementation-defined; the value returned shall be either
  a null pointer or a unique pointer."

We believe that ptr=malloc(0) and free(ptr) is now handled properly, so
it's no longer necessary to short-circuit our PetscMalloc.  This allows
memory checking tools to match size-0 allocations and frees if they so
choose.
Merge branch 'jed/malloc-zero' into next

* jed/malloc-zero:
  PetscMalloc: allow ptr=malloc(0) and free(ptr)