Add epetra matrix format, with aztecoo and amesos

This adds the epetra matrix format and the AztecOO solver, epetra is only usable with AztecOO and Amesos.

`docs/epetra_matrix_format.md` contains some more information about changes

This avoids the conversion from MSR to Epetra at each solve for amesos, and it looks like Trilinos does a similar thing when solving aztec problems with AZ_solve.

The ac_loca solve loop isn't supported I'm unsure if this should be supported or not it looks like amesos is not supported their either.

Passes test suite.

Also Passes test suite with Amesos/ Aztec problems converted to use epetra with only very minor differences on a couple problems. I'll add a couple of these problems to the test suite after this is accepted.

I haven't done much testing on if this improves speed or memory usage yet.