*Created by: ccober6* Adding a Stepper initial conditions has several benefits: * Ensure that the initial SolutionState is consistent, i.e., x, xDot, and xDotDot satisfy the governing equation at the initial time. * Currently explicit Steppers are not consistent until the next time step fills in the currentState. This change will make the SolutionState consistent within the time step. * For explicit Steppers with a consistent SolutionState, the residual can be determined and compared to residuals from implicit Steppers. This is SPARC's main driver for this change. * For DAEs, making the initial condition consistent is critical to obtain the correct solution. @trilinos/tempus ## Expectations * Changes for this issue should not effect solutions. ## Definition of Done - [x] First convert Forward Euler. - [x] Convert all other explicit Steppers, ERK, Leapfrog, ... - [x] Convert all implicit Steppers - [x] Passes all tests.