UGLY COMMIT
Refactored out a lot of the scheme specific behavior
Intermediate state save. Going to work on saving and loading meshes for
a little while.
Forgot to add boundary_cond.h
Implemented grid saving and loading, because I got annoyed at waaiting.
It was super easy and I should have done it sooner...
Magic! BDF2 scheme seems to be working.
Some bc fixes. No testing if not desired.
Fixed some garbage collection problems. Compartmentalized code some
more.
Small fixes before merge