updated PETSc directory layout to match standard packaging strategies

include/petsc finclude,private,mpiuni
lib/petsc conf
bin/petsc*

Optimized MatShift() for a completely empty matrix since this is commonly used with SLEPc to produce diagonal matrices

Reported-by: Jose Roman <jroman@dsic.upv.es>

elemental: move MatElementalHermitianGenDefEig() prototype into include/petscmatelemental.h

make prototype of MatElementalHermitianGenDefEig() consistent with HermitianGenDefEig()

update MatElementalHermitianGenDefEig_Elemental(); build works now

elemental: more 0.85 fixes including:
'HermitianGenDefiniteEigType' to 'Pencil' and 'HermitianGenDefiniteEig' to 'HermitianGenDefEig'

Also change MatElementalHermitianGenDefiniteEig() to MatElementa

elemental: more 0.85 fixes including:
'HermitianGenDefiniteEigType' to 'Pencil' and 'HermitianGenDefiniteEig' to 'HermitianGenDefEig'

Also change MatElementalHermitianGenDefiniteEig() to MatElementalHermitianGenDefEig() to correspond
to elemental naming scheme?

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elemental: update petsc interface to 0.85 [elemental.hpp -> El.hpp] [elem: -> El:]

add MatConvert_sbaij_elemental()

fix a small mem leak; valgrind still shows leak in commgrid->grid, don't know how to fix it yet :-(

add #include <elemental.hpp> into petscmat.h so elemental data type can be used for API routines

add MatLoad_Elemental(): = MatLoad_dense + MatConvert, could be very slow!

cleanup

continue working on MatElementalHermitianGenDefiniteEig_Elemental()

test eigenvectors in MatElementalHermitianGenDefiniteEig()

MatElementalHermitianGenDefiniteEig() gives evals as an output (PETSc mpi vec)

add interface to MatElementalHermitianGenDefiniteEig()

prepare to add MatElementalComputeEigenvalues() -- may rename it later

manual merge of conflict