[melodic] Adding SIP 5 integration.

[seanyen]

This is an attempt to implement SIPv5 integration. Since SIPv5, it started to implement PEP 517 compliant backend and stopped releasing sipconfig module.

To integrate with it, one can define PEP 518 (a.k.a., pyproject.toml) project file to describe the SIP build. And here are the minimum requirement to run:

• Python>=3.5
• SIP>=5.0.0
• PyQt5-sip>=12.7.0
• PyQt5>=5.14 (and the respective Qt development SDK)
• PyQt-builder>=1.0.0
• Pip>=19.0 (https://pip.pypa.io/en/stable/reference/pip/#pep-517-and-518-support)

And here is some highlights of my verification environment:

• Windows 10
• Python 3.8.3 (pip-20.2.1, setuptools-49.2.1)
• Qt5 5.15.0 (Vcpkg port)
• Installed python modules:

PyQt-builder==1.4.0
PyQt5==5.15.0
PyQt5-sip==12.8.0
sip==5.3.0

[dirk-thomas]

Can you please provide some more context: e.g. what minimum version of sip / setuptools is required for this patch to work, if you have verified this still work on e.g. Ubuntu with the Debian packages or with a newer version of SIP, etc.

[seanyen]

@dirk-thomas I tried to capture the minimum requirements specified on the book (also added more matrix on Windows side). For the Linux validation, I found it is little bit tricky to have a system with Qt>=5.14 plus all other Python required modules. Please excuse my limited knowledge on Linux side, do you just happen to know what distro \ release I can begin with first to get a closer environment?

[jspricke]

@seanyen Debian unstable/testing has all the packages in the required versions.

[sloretz]

@seanyen Is this PR still relevant after #95 and #105?

[lopsided98]

I think this PR is still required to build python_qt_binding with SIP >=5. SIP 4 is currently still required to build this package, those other PRs just allow this package to work in combination with PyQt5 built with SIP >=5.