completed update of PETSC_EXTERN_C usage to replace EXTERN_C_BEGIN/ENDHg-commit: 84182841dc78e38819f60460c0b7afa4c601fbd6
moved ao over to vec/is locationfixed couple mistakes in examples made by privitizing petscimpl.hHg-commit: 01295422394106db7c66f43df1606e60d84f7325
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