Add capacity expansion limits for biomass and geothermal.

[trevorb1]

With pr #102 we introduced a zero global geothermal capacity expansion limit, as it was clearly being overvalued. As from the pr thread...

It would be useful to set up a file of domestic fuel reserves by country. I imagine the IEA must have something on these lines.

We should check if we can find country level fuel reserves, and use that to set capacity expansion limits on a technological and regional level.

[maartenbrinkerink]

Also relevant for biomass see #104.

[DuncanDotPY]

Hey @maartenbrinkerink, I have used the Geothermal potential from this paper (see supplementary data for national potentials) in building on PLEXOS World. You might find it useful for this.

[maartenbrinkerink]

Much appreciated @DuncanDotPY! In PLEXOS World did you downscale it further to regional level or kept it as a national constraint?

[DuncanDotPY]

I kept it national - but the source linked above does actually provide it at regional level for many of the sub-national regions e.g. China, Russia, but not all regions, e.g. Australia).