[new feature] Support more ensembl genome, such as plants and fungi

[y9c]

https://plants.ensembl.org/index.html

[y9c]

• install rice reference genome by:

pyensembl install --species rice

• install Arabidopsis reference genome by:

pyensembl install --species cress

[y9c]

Hi @iskandr,

I would like to follow up if there is a plan to support more species.

[iskandr]

I'm open to it!

I closed the PR with rice support (#295) because it touched way too much code (and had some mistakes and merge conflicts). Can we add plants and fungi in a more granular fashion? And, if it requires switching between multiple source servers can we change that code first before adding new species?