Improve build procedure building from setup.py.

[jpivarski]

Still to do:

• Fix install location of python & so files (currently in .env base dir!)
• Restore non-Scikit-build build (since Scikit Build 0.11 has not been released yet, and 0.10 does not support Python 0.10, see Can no longer build on macOS scikit-build/scikit-build#362)

[jpivarski]

Some baseline compilation times on a slow (Chromebook) computer:

• full compilation time in release mode

real    3m20.192s
user    3m10.504s
sys     0m12.654s

• linking-only in release mode

real    0m52.832s
user    0m50.578s
sys     0m3.352s

• full compilation in debug mode

real    4m49.084s
user    4m45.499s
sys     0m14.281s

• linking-only in debug mode

real    0m8.494s
user    0m6.615s
sys     0m1.735s

That's an interesting trade-off.

[jpivarski]

@henryiii I've fully merged in #130 and tested it, including ArrayBuilder in Numba (which uses ctypes to access libawkward.so).

[henryiii]

Remember, we need to manually squash to 2-3 commits then rebase and merge, since we do a large renaming and several edits; if we just squash and merge git will loose the history tracking on the python files in src/awkward1. Let me know when you are ready and I can do it.

[jpivarski]

@henryiii It's ready. Please do it.

[jpivarski]

I copied this branch as save/PR129-henryiii-build-procedure.

[ianna]

@jpivarski and @henryiii - nice work, local builds are a lot faster! Thanks!