Poisson: add size as optional command line argument
Advection-diffusion: update meta
Advection-diffusion: memoize meshes
Advection-diffusion: tune AMG parameters
Advection-diffusion: add weak scaling support
Advection-diffusion: improve plotting for sequential/parallel/weak
Poisson: configurable AMG parameters
Poisson: add verbose option
Advection-diffusion: configurable AMG parameters
Advection-diffusion: add verbose option
Advection-diffusion: default AMG strong_threshold to 0.25