Added some error handlers and robustness checks for setup script Fixes #32

Hi iconarray-team,

Big fan of the project and first time contributor (but longer time user).

Here some reasoning for the stuff I changed in the setup file:

$HOST is sometimes not defined in non-login shells, using $(hostname -s) is more robust. This can be important for VSCode users for example
Made sure that if module loading fails, the script aborts and returns an error message
The ~-sign has to be escaped when working in zsh, in bash both \~ and ~ work
My default formatter changed ` to$()` syntax, which I think is clearer to read and less prone to quotation mark errors
Copying the cartopy script failed because of non-matching Python versions, the Python version retrieval is now automatic
Added some error messages

C2SM / iconarray