Make exploratory toy

[ICWallis]

Make a version of the power capacity calculation where the user can interact with sliders. The aim is to make this a 'toy' version where people can play to understand how it works. May be cool to include something that shows a sensitivity analysis (how much do the different input parameters impact the P10, P50 and P90 power capacity). Open to suggestions. Just opening this as an issue so we have somewhere to discuss.