Up to now, there was a central list of variable name patterns that
defined whether a variable was printed as a sorted list, as a list or as
a single value.
Now each variable group decides on its own which of the variables are
printed in which way, using the usual glob patterns. This is more
flexible since different files sometimes differ in their naming
conventions.
Two variable groups are added: license (for everything related to
LICENSE) and go (for lang/go).
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