Added lots of functions and macros for the species DSL

docs/src/nature.md

src/analysis/makieplots.jl

src/core/simulation.jl

src/crop/farmplot.jl

src/farm/farm.jl

src/nature/ecologicaldata.jl

src/nature/macros.jl

src/nature/nature.jl

src/nature/populations.jl

src/world/landscape.jl