Be more pedantic.

./json.h:67:9: warning: anonymous types declared in an anonymous union
      are an extension [-Wnested-anon-types]
More pedantry.

warning: overflow in implicit constant conversion
Avoid a warning

cio.cc:340:76: warning: format ‘%p’ expects argument of type ‘void*’,
        but argument 2 has type ‘input_history*’ [-Wformat=]
Document vault tech (nicolae)

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Document an enum order dependency.

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