Work on comparison of renormalisation and mid-point method

* Rewrote plotting script.

* Small improvements to data processing script (it still sucks...).
** Can now get data at a certain time
   so long as the output is rounded properly...

* Fixed a minus sign in analytical calculation of t(theta)

* Added mid point method

* Increased output precision
  Some errors were going below rounding error.

* Parallelised and cleaned up python parameter sweeping loop
  Basically a rewrite.

* Fixed mid-point method in ImplicitLlgProblem
  It wasn't updating the time correctly after the half step.
  Probably needs a beter implementation...