Poisson: add parameter to select preassembly
Poisson: add parameter to select preconditioner
Profile Poisson by default
Update PyBench
Call archive at the end of Poisson
Poisson: adjust number of processes
Navier-Stokes: move meshes into subdirectory
Update PyBench
Poisson: add plot over polynomial degree

Also override xvalues and xlabel.
DOLFIN advection-diffusion: reorder mesh in serial
Advection-diffusion: don't output norm by default
Advection-diffusion: enable profile by default
Advection-diffusion: use meshes with doubling number of DOFs
Advection-diffusion: run on 1, 2, 3, 6 processors
Advection-diffusion: add plot over polynomial degree

Also override xlabel and xvalues.
Update PyBench
Poisson: use default colors
Advection-diffusion: use default colors
Navier-Stokes: use default colors
Advection-diffusion: don't plot timestepping region