According to the online documentation (https://www.sqlite.org/series.html),
generate_series is compiled into the command line shell. As it turns out,
this is not so. It is not even an option in the build system from what I
can tell. It would be nice to at least have a build flag to enable it.
I searched the list archives and noticed an email from late 2015 that
indicates that generate_series was never actually a part of the shell.
Apparently no one ever took up the task of making that happen. Would it be
okay if I put together a patch for this? I would prefer it to be enabled by
default, but I can implement it either way.