Fix caching

See merge request !7

with the code before, the periodic iters for the preconditioner were
updated only if the matrix was changed. Now, periodic updates are decoupled
Added PC setup stage to better distinguish low level PETSc events

- for OpenFOAM-v2006 shifted the location of flange.ans into tutorial
  resources specifically to make tutorial tests easier for this add-on
  solver.

  Only attempt to copy flange.ans for older versions to avoid spurious
  error message for new versions.

- unused fall-through value, but should default to "Always"

- easier to add/change in the future.

- copy PETSc fvSolution to the system/ directory to ensure no
  issues following symlinks on cluster jobs

- remnants from older code prior to wrapping PETSc vectors directly.

- leave gAverage() and gSum(). Still potentially useful.

- might have PREFIX/ARCH/include PREFIX/include

- setup without hypre as the safer choice.
  PETSc may not have been configured with hypre.

Add test for petscFoam loading to top-level tutorials/Allrun

TUT: added the optimization

   ksp_norm_type   none;

to all CG ksp solvers.

    libs            ("libpetscFoam.so");

to get more link regular command

    libs            (petscFoam);

- change very misleading enum from `cachingTypes` to `updateTypes`
  and fix enumeration order.

- default constructed cache was "None" (meant to be no caching)
  but should have been "Always" (ie, always update).