Unify conda instructions

[IAlibay]

The python, docking and homology modelling tutorials (and soon the MD tutorials), all have separate conda setups. These should be unified so that students only have to set up conda environments once at the start.

That or we should be providing unified install instructions, i.e. yaml files with a clean description of which environment to build & use for each tutorials. We definitely shouldn't be telling anyone to conda install outside of an environment.

[philbiggin]

They will have separate instructions because people may only elect to do one or some of them.

[IAlibay]

Makes sense, it would still be good to have a unifed "method" for installs, it's hard to explain what I mean, but essentially it involves moving all that's conda-able to yaml files. I'll try to push a prototype PR this weekend (maybe after the MD tutorial).

[IAlibay]

In the end unifying was too much of a pain, particularly because some of the conda envs required specific installs that don't always play nice with everything else. In the future we'll have to more thoroughly test all this. Putting it as a milestone for 2021.