Tie::File::Hash learns EXISTS method
00meta module learns meta::has_key
00meta correct handling of HAS key

Unlike other keys, it should not be lowercased
better diagnostics in 00meta
Major rewrite of article selection code in nonotyet plugin

I made terrible mistakes about which articles were selected for
publication the last several times I republished the blog.  The
nonotyet logic is complicated, with many cases, and needed to be given
a more straight-line structure where the decisions were more explicit.

Better diagnostics too.