pptk Changes necessary to compile on arch linux (py38)

I've made some necessary changes to compile pptk and create a wheel file for me on Arch Linux with Python 3.8. This solves both https://github.com/heremaps/pptk/issues/37 and https://github.com/heremaps/pptk/issues/39. I have tried to ignore the Windows and Apple sections and leave them mostly alone, but I would not expect this to work on those platforms without more modifications. Hopefully someone can expand my work and address those issues.

Here is the wheel file for convenience: pptk-0.1.1-cp38-none-manylinux2014_x86_64.zip

To solve issue https://github.com/heremaps/pptk/issues/39:

Removed old Find*.cmake files to use the ones provided by the system packages, and made necessary changes to multiple CMakeLists.txt to use those. Switched to imported targets.

Changed imports of numpy heders in cpp files to be compatible with the folder structure provided by system packages.

To solve https://github.com/heremaps/pptk/issues/37:

Modified setup.py to be compatible with pip 20.

Feedback would be appreciated, especially if this compiles on other systems. @victoriousluser I hope you can use this to add a wheel file to PyPI?

Sep 17 '20 19:09 cassfalg

Is there a reason You have bumped the minimum required CMake version?

Sep 23 '20 17:09 kamiccolo

Yes. Is that a problem for you? Can you try what fails and offer alternatives?

The FindPython module requires 3.12 according to the docs, and something else (don't remember atm) required 3.14 so I put that everywhere. It is not necessary everywhere and I have not tested or tried to push it down. I don't really want to either.

Sep 24 '20 21:09 cassfalg

Yup, You're right. Just trying to be careful with those bumps :} Not every distro has this fast pace with package versions...

Can't build pptk anyways :D

Sep 24 '20 21:09 kamiccolo

Nice, hope that this will be merged and whl would be updated..