Fixed compile error on Windows.
Fixed xsd install path.
fixed missing slash in save-file-settings
fixed index error for matgroup in 3d geometry
[MathLib] PETScMatrix style.
Fix warnings in tests.
fixed normal vector for surface extraction (was overlooked when changing node numbering a few months ago)
Merge pull request #409 from TomFischer/FixWarnings

Fix warnings and docu improvement.
Removed one member function of PETScLinearSolver
Merge remote-tracking branch 'ufz/master' into pr_petsc_solver