LinAlg → PETSc Relation

File in MathLib/LinAlg	Includes file in MathLib/LinAlg/PETSc
ApplyKnownSolution.h	PETScTools.h
LinAlg.cpp	PETScMatrix.h
LinAlg.cpp	PETScVector.h
MatrixVectorTraits.h	PETScMatrix.h
MatrixVectorTraits.h	PETScVector.h
UnifiedMatrixSetters.cpp	PETScMatrix.h
UnifiedMatrixSetters.cpp	PETScVector.h