[HIGH]: remaining plotting PDE to-dos

[mathematicalmichael]

• convergence figures need updating on y-axis limits
• proper comparison for pde example in the above (distance to projection) (see [HIGH]: pde convergence plots in dim > 1 #36)
• y-axis limits in convergence plots should work for both pde and ode
• some semblance of documentation in README
• log crashes when all estimates identical. need better handling.