(Info-tagify): Don't insert more than one newline before the tag table.

(Info-tagify): Don't insert more than one newline before the tag table.

(Info-tagify): Start by widening.
Match node headers that don't list the file name,
and more kinds of page separations.
Strip properties during tagification.
Use start of node header line as tag's position.
Fix the "done" message.

(Info-validate): Save and restore match data around narrowing down.