Bounded parallelism and CPU Cores usage chart

[Saizan]

• Added rather crude chart to show number of cores used per node.
• TODO: moving average might be more illustrative.
• Added -N flag to control parallelism, accepts 'unbounded' or number of cores.
• cabal run ols -- viz short-leios-p2p-1 -N unbounded shows a node using 13 cores around 30s.
• Otherwise things seem to get busy around votes, though maybe less so as time goes on?

[wenkokke]

Added -N flag to control parallelism, -1 unbounded, otherwise that many cores.

Why not use 0 or a "unbounded" for unbounded usage? (Or --max-cpu-cores=N versus --no-max-cpu-cores?)