Prepare to implement FB2 downloading
Print error returned by Close (if any) to stderr
Parametrize download handler; return zip archive with empty .fb2 file
Use new Flush func
Write some XML to zipped .fb2 file
Move notabenoid downloading code to the separate file
Ignore errors from zip writer
Add fb2 download form with book requisites
Keep variables inside one var statement
Don't complain about unsupported HTTP method
Improve templates