Update PyBench
Poisson: refactor to group by variant
Advection-Diffusion: refactor to group by variant
Navier-Stokes: refactor to group by variant
Cahn-Hilliard: refactor to group by variant
Forms: refactor to group by variant
Update PyBench
Forms: plot speedup relative to DOLFIN
Forms: rename degrees of functions to p and q
Firedrake forms: enable COFFEE vectorisation
Update PyBench
Forms: adapt mesh sizes with polynomial degree
Forms: run only for 3D