formatter: populate ctx from repo and node value
This will basically replace the fm.contexthint() API. I originally thought
this would be too complicated, and I wrote
8399438bc7ef "formatter: provide
hint of context keys required by template" because of that. However, I had
to add a similar mechanism for fctx templates, and the overall machinery
became way simpler than my original patch.
The test output slightly changed as {author} is no longer available in
the {manifest} context, which isn't the point this test targeted on.
#require docutils gettext
$ $TESTDIR/check-gendoc it
checking for parse errors