add MatElementalHerk()

implement MatElementalSyrk()

start adding MatElementalSyrk() -- not implement yet

a variety of fixes for issues detected by the clang static analyzer

Reported-by: clang static analyzer

nightlybuilds: fix compile errors.

set solvertype for inplace MatxxxFactor()

Fix null output from PCFactorGetMatSolverPackage();
Reported-by: Jose E. Roman <jroman@dsic.upv.es>

some uses of PetscTryMethod() actually require that the

object is correct and the function returns an appropriate value.
Change those calls to PetscUseMethod().

More decreasing visibility of symbols from outside libraries
Also fix a few bugs related to having multiple PETSc libraries

fixed up formatting of references in manualpages to consistent style

References:
+ 1. - ref1
. 2. - ref2
- 3. - ref3

previously the formatting was varied and ugly