Prepopulate additional non-stated settings with its default value

[egberts]

Might be more useful if the unstated settings (of named.conf) has its default values and seeded in the final PyParsing object tree.

[egberts]

Probably best done outside of PyParsing effort.

Perhaps as an added .seed_with_defaults Python method added to the bind9_parser Class or something.

[egberts]

Definitely have to be given a version number before default values can be determined, which is to be expected anyway