lfs: add the '{lfsattrs}' template keyword to '{lfs_files}'
This provides access to the metadata dictionary contained within the tracked
pointer file. The OID is probably the most important attribute, and has its own
keyword. But we might as well have this for completeness.
I liked {pointer} better, but couldn't make it work with the singular/plural
forms.
#require docutils gettext
$ $TESTDIR/check-gendoc da
checking for parse errors