Add silent mode.
Simpler way to use `include-template`.
Add 'date-8601 and 'date-struct template variables.

Document the need to use `local-require` instead of `require` in a
template.

Add example showing all of the above.
rm pre-base.rkt

Should have included this with commit 07c1f8d1, as of which the file
no longer used.
Bump to v0.11