Revise visualisations

[ekatef]

PR aims to make visualisations more clear for a modeller. Main changes introduced:

1. added a generation and load parameters for the spatial plot (partially addresses Add content to spatial plots #9);
2. generators to be shown by color filling are filtered to be renewable only (partially addresses Add content to spatial plots #9);
3. revised layout for System Operation: only Suppy and Demand plot are left at the moment to keep the focus;
4. revised labels and content of Suppy and Demand plots (partially addresses Improve time-series plots #10)

[ekatef]

Hello @drifter089! Have revised visualisations a bit.

The idea is to make plots correct and as nice and clear as we can, as the first step. Once we'll be happy with the results, the commented-out plots and selections can be get back.

Feel free to disagree and comment on the suggested changes :)

[ekatef]

@drifter089 @pz-max I believe that is ready for review 🙂

[pz-max]

Feel free to merge after review from @drifter089

[pz-max]

Reviewed and merged. Just found this issue here that there is two times p_nom (nominal power with somewhat different results being plotted)

[ekatef]

Reviewed and merged. Just found this issue here that there is two times p_nom (nominal power with somewhat different results being plotted)

Thanks for review @pz-max! There are currently both p_nom and p_nom_opt, although agree that p_nom is not very meaningful and can be misleading. Fixing it.