Just read the JSON from a file and decode it every time it's needed.
This is just the validator now.
No need to support old CPAN stuff. Also, document undocumented validator methods.
In the spec, all lists are allowed to be lazy.
In passing, eliminate `custom_1` and rename `custom_2` to just `custom`. Also, delete `module()` in favor of `term()`, and add `tag()`.
Support a list *or* a map of licenses. Done by adding a new checker, `listormap`. While at it, start adding more tests for valid metadata, too.
Require the `provides` key and make sure that versions are valid semantic versions (or 0 for prereqs). Also allow "abstract" and "docfile" keys under `provides`.
Fix some bugs found as a result.