refactored CreateBasisFromPlex like ratel

Created label like ratel, added DMViewFromOptions

Fixed the uncompatible restriction size.

Added TESTARGS for simplex in bps.c and multigrid.c

Used "CeedOperatorMultigridLevelCreate" to create multigrid operators

example/petsc: Added CreateDistributedDM in petscutils.c and some cleanup

example/petsc: added CreateBasisFromPlex and tested with tensor basis

petsc - drop VecZero in diag assembly

examples/petsc: fix missing PetscFunctionBegin

vec - use CeedSize for vector lengths

examples/petsc: let DMSetFromOptions manage distribution

Sphere meshes are automatically snapped to the unit sphere when refined.

I left explicit partitioning in solids (though Ratel uses the new
p

examples/petsc: let DMSetFromOptions manage distribution

Sphere meshes are automatically snapped to the unit sphere when refined.

I left explicit partitioning in solids (though Ratel uses the new
paradigm) because it has documented command-line arguments and maybe
someone wants to know how to avoid this distribution.

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examples: skip DMPlexLabelComplete now that PETSc does not need it

petsc - set minimum version for examples

style - make qf/op field names human readable

petsc - use DMPlexGetLocalOffsets for building restrictions

petsc - use PetscFECreateLagrange

petsc - clean up some header inclusions

petsc - new compatibility macro for DMAddBoundary

style - update to new style for petsc examples

petsc - move Kershaw transformation to petscutils

petsc - refactor examples to reduce redundant code