docs: metrics: Split engine-speed/power in 2 plots and beaty them.

* ver: bump from 0.0.9-alpha.1-->alpha.2.
* model: Methods for class and part limits, with TCs.
* pandel: Methods to resolve and set json_pointers, with TCs.
metrics: Add Arrows-plot on pmr-->n.

* plots: Move plots into main-code.