510 python 3 + gippy 1.0 gips port

[ra-tolson]

Fixes #510 depending on whether you count the necessary brokenness discussed in that issue.

This PR is massive so I'd suggest a staged approach, where we take the 115 files changed and divide them up into logical blocks and handle them piecemeal. I'd suggest:

• install & config files related to docker and pytest and gitlab's CI pipeline (everything in the root directory and docker/ basically)
• Changes to automated tests (many changes are just expectations moving around, so goes fast even though it's a lot of diff)
• Core/engine code such as gips/utils.py and core files.
• drivers, one driver at a time
• maybe split off big blocks into smaller ones as needed

I'll be reading through this diff as well since I didn't write some of these commits and I want to confirm the final diffs look okay.

[ra-tolson]

Ooh there's a nice "0 / 115 files viewed" and some clicky buttons in the Files Changed tab. That looks pretty handy for staying organized.