Update code

Minor changes:

• !10 (closed)
• !11 (closed)
• !12 (closed)

Bug fix:

• #34 (closed)
• Incorrect handling of caching dictionaries

plus a more extensive set of changes to solve #2 (closed).

Handle PETSc errors with two macros:

• AssertPETSc is meant to be called within OpenFOAM methods that calls PETSc
• PetscCall, instead is intended to be called within callbacks used by PETSc