Essential:
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Show response after submission
Require earliest and latest dates for creation
Ensure latest date is at least earliest date
Ensure date span is within a maximum
Add timeout to request context
Prevent blank event names and guest names
Consider some front-end, regex-based field validation
Consider redirecting from /create/do to admin

Cleanup:
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Give response (and therefore response_time) a composite key
Get rid of the Stat call in NewStore.
    I can't remember the details. I think the old version
    of sqlitex was panicking if I failed to open a DB file.
    Maybe instead of statting, I would try to open an
    existing file, but instead create it on failure.
Add optional subtitles to (*front.handler).writePage
    Take a Page struct with title, subtitle, and contents.
Make titles optional in (*front.handler).writePage
Make the sqlite pool size configurable


More features:
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Show validation errors in a header, rather than on their own page
Allow updating metadata on admin page