* We don't need it to have an argument, can just detect used build system.
* We now check if setuptools is actually used.
* Move the handling of the project tool to dedicated modules in a
new package "nuitka.options" where long term option parsing will
go as well.
* We also prepared passing the requirements to install via command
line options, but that's not usable yet.
* The test case added lately was Python3 only, but rather than extending
the list, lets just use filename driven decision, migrating to proper
test case scan.
* To make it work, we needed to rename cases, such that numbers are not at
the end, or else they will be mistaken for version constraints, e.g. "_2"