* In a previous update in 2021 many copyright ranges were truncated
accidentally, and some files have been copy-pasted with wrong years. These
dates have been fixed based on git history and original copyright messages.
* This allows persistent config storage and registering tweak variables that
works independent of the UI's configuration.
* Config vars can be debug only, which means they will be compiled out in stable
version releases. This allows for debug-logging tweaks that are available in
all builds (including nightly builds) for diagnostic purposes, but have zero
overhead in stable releases.
* Variables have a loose hierarchy defined with _ or . to separate nodes.