Pre-requisites for ubuntu install

[jphuart]

I've added into the install.sh script comments on the needed pre-requisites packages to ensure that the SAW works on a Ubuntu 20.04 OS. Maybe it could be improved adding how to do it for other distributions.

I've modified the swatplus_aw.sh script to use the correct modules and to match the functioning of the .bat script.

[jphuart]

Last error was on the weather generator database, I've downloaded from bitbucket SWAT+ editor repository.

[celray]

Do you think we should change to $HOME instead of $SWAT_HOME in the update for the latest SWAT+ release?

There are still some tests I have to do but I still have time to adapt it if $HOME Makes more sense

[jphuart]

I was surprised about your message, now I understand what happens. I'm trying to define the easiest way of using this project in an isolated conda environment. $HOME variable is not suitable for this, I wanted then add a variable that can be set to the path of the conda environment path. I've called in a first test SWAT_HOME, which is a mistake, at least it should be called SWAT_AW_HOME. By the way, what I'm doing is not ready yet, I will continue on this in may. I will propose a proper pull request when it will work fine.

[celray]

Perfect, SWAT_AW_HOME sounds good. I will keep an eye on this. Thanks.