opinionated structure changes, fix build process, fix test, use local project for tests, semantic versioning

[benatouba]

Hi,
thanks for the module. I'm offering you some changes/updates. Feel free to pick whatever you like or block.

• fix the build process
  • it did not throw an error before but neither did it install anything
• change the project structure.
  • It now contains a folder with the project name inside, where the code is.
• changed the tests to use/import local files.
  • I think this speeds up the iteration when fixing/writing tests (No need to install in between)
• more elaborate pyproject.toml
  • It now sets clear style guides and some more stuff
• Fix test
  • the test for solar radiation out-of-bounds seemed odd to me. I changed it. Please check if correct.

Again thank you and I hope you find my changes helpful.

Best regards

P.S.: Might have messed up your gitignore, but that was in a subfolder before anyways.