Duration wraps time.Duration to provide json serialization and deserialization.

Flag represents a ternary value: false (-1), default (0), or true (+1).

Priority represents a value with a priority where 0 means "default" and -1 means "disabled".

Strings is a helper type that (un)marshals a single string to/from a single JSON string and a slice of strings to/from a JSON array of strings.