Pierpaolo Da Fieno

Support per-requirements overrides (--install-option and --global-option flags)

33

## The problem Since version 7.0 pip allows the usage of *--global-option* and *--install-option* individually for each requirement in requirements.txt (https://pip.pypa.io/en/stable/reference/pip_install/#per-requirement-overrides). It is in principle possible to use environmental variables...