Support Newer Swift Versions & Dockerization

[Kaiede]

Swift 5.1.5 is getting pretty old at this point, but it’s the latest version of Swift supported outside of 64-bit.

That said, it’s possible to use newer versions of Swift on 64-bit Raspbian, so it becomes a dilemma. Should SingleBoard continue to try to support the latest version of 32-bit Swift available? Should SingleBoard focus on 64-bit Raspbian?

One of the issues is that the current access to the PWM registers requires access to raw memory. Outside of Raspbian, this hasn’t been very straightforward and requires undoing an awful lot of locks on the kernel that exist for a good reason on Ubuntu and other platforms, while Raspbian remains friendly to this sort of poking and prodding.