Beta PR 1 of 2: subject-ID range review

[pavel-kirienko]

• Fix https://github.com/UAVCAN/specification/issues/94
• Provide config for SpellRight in the VSCode settings file.
• Update the spelling dictionary -- some of the words were located in my personal dictionary on my workstation; now everything is kept in the repo.
• Switch the Public Regulated Data Types submodule to https://github.com/UAVCAN/public_regulated_data_types/pull/80
• Switch the PyDSDL source from PyPI to https://github.com/UAVCAN/pydsdl/pull/45 to support the changes introduced by the above (otherwise it won't compile). Will switch back to PyPI after PyDSDL v1.6 is released.

@TSC21 @dimracer this is the first of the two PRs that separate us from the beta.

[thirtytwobits]

Please update the .vscode/Dockerfile to use the 18.04 texer image. The 16.04 version is no longer able to build the specification apparently.