Find tag (in current tags table) whose name contains TAGNAME.
Select the buffer containing the tag's definition, and move point there.
The default for TAGNAME is the expression in the buffer around or before point.
If second arg NEXT-P is t (interactively, with prefix arg), search for
another tag that matches the last tagname or regexp used. When there are
multiple matches for a tag, more exact matches are found first. If NEXT-P
is the atom `-' (interactively, with prefix arg that is a negative number
or just M--), pop back to the previous tag gone to.
If third arg REGEXP-P is non-nil, treat TAGNAME as a regexp.
A marker representing the point when this command is invoked is pushed
onto a ring and may be popped back to with M-*.
Contrast this with the ring of marks gone to by the command.
See documentation of variable `tags-file-name'. (fn TAGNAME &optional NEXT-P REGEXP-P)