Remove ModuleThemeInterface::parameters

[fisharebest]

This was legacy code from webtrees 1.

Most of the parameters have been replaced with CSS.

The rest need to be removed too.

[jon48]

Is there any chance to restore some flexibility in the choice of colours that were associated with the removed parameters?

In 34b20f2, all those parameters have been replaced by hardcoded values, but not all themes (even amongst the standard ones, most notably the Minimal theme) were using the same colour palette for the chart-background-* and distribution-chart-* as those hardcoded ones. I have been using specific colours in the Rural theme as well.

What bother me a bit is that:

• for the chart-background-* ones, the male and female colours do not necessary match the standard male/female colours scheme on other pages any more. In the Rural theme for instance, I am using tones more pale than the webtrees theme, to match the overall tone balance, as the default colours are too "flashy" for my taste.
• for the distribution-chart-*, I am not keen in using a colour, which is gender-connotated - blue- for charts that have nothing to do with genders, so I had used a more neutral colour in the Rural theme on purpose (brown, the same way grey tones were used in Minimal).

I have tried playing with CSS on the Google Charts, but there are not enough selector available to override the default colour.

[fisharebest]

We need these colours for the fan-chart and the google-charts. Both need to be replaced.

The fan-chart needs to replace PNG with SVG. We will be able to style this using the theme's CSS.

The google-charts need to be replaced completely. See #3883

If you want to suggest more neutral colours that will work with a wide range of themes, then please do.

[jon48]

If there are plans to replace those charts, with alternatives that will allow to use the CSS styling , then I am happy to wait, and temporarily fall back to default colours for the time being.