introduce pyproject.toml

[lvxnull]

Installation through pip is broken(it installs to /usr/lib/python<ver>/site-packages/src instead of something sensible like nautilus-open-any-terminal). To fix this you must either change the project file layout to match one of the supported setuptools project layouts or find a way to tell setuptools that the module under src is actually called nautilus-open-any-terminal.

[Stunkymonkey]

I guess this originated from the setup.py, because it reads the folder where the files are located. So I simply reverted the renaming. If we really want to do it we should do this in another PR. This one is already big enough.