Add some polynomial solutions
Write out exact solution from ode problem
Fix get mass matrix function to correctly calculate residuals
Switch the sign of the residual in ode problems

This is required to make explicit time steppers work!
Separate time adaptive newton from ability of timestepper to adapt

We want to be able to calculate ltes without adapting. So need to always
have adaptive enabled time steppers but be able to choose whether to
actually adapt separately.
Comments and extra output in ode