Add residuals generator for class of odes which are very bad for midpoint
Add some simple configurations for the llg residuals
Tidy up some residual/dydt/step functions
Add tr lte + scheme generation and some debugging tools elsewhere

* Add tr lte

* Add test to make sure correctly generate tr ab adaptive scheme

* Tidy up assertions in generate_predictor_scheme

* Add "wrong step ebdf2" predictor
  Using the wrong step size seems to work for some reason, need to figure
  it out...

* Add lots of debug output in generate_predictor_pair_lte_est
Add a test making sure we can generate adaptive ebdf2 scheme