Reevaluate chart libraries

[tsa96]

Whilst doing the map approval section of the map edit page, I used Chart.JS as I wanted something quite and easy, and PrimeNG comes with a wrapper component for it.

However Chart.JS is canvas-based, looks crappy by default, and can't be configured much. I probably should've stuck with echarts, but to be totally honest, I completely forgot it existed and picked between chart.js and D3/D3 derivatives.

We intend to do a lot more graphing in the future, just because I picked Chart.JS for this simple thing shouldn't mean we get stucked with Chart.JS in the future. My hunch is we'll go with ECharts.