Configure a complete setup.py script

Description

We require a setup.py script that enables one-line installation of icet via e.g.,

python3 ./setup.py install --user

The C++ module should be compiled as part of the process.

Sub-tasks

• configure basic setup.py script
• add C++ compilation
• integrate setup.py in CI

Demonstration

• all tests pass
• installation works on "blank" docker image (see issue materials-modeling/hiphive#142)