Parse a document title as the first line starting in [A-Za-z0-9<]
           or fall back to the document basename if no such line exists.
           The cmake --help-*-list commands also depend on this convention.
           Return the title or False if the document file does not exist.

def parse_title(self, docname):
        """Parse a document title as the first line starting in [A-Za-z0-9<]
           or fall back to the document basename if no such line exists.
           The cmake --help-*-list commands also depend on this convention.
           Return the title or False if the document file does not exist.
        """
        env = self.document.settings.env
        title = self.titles.get(docname)
        if title is None:
            fname = os.path.join(env.srcdir, docname+'.rst')
            try:
                f = open(fname, 'r')
            except IOError:
                title = False
            else:
                for line in f:
                    if len(line) > 0 and (line[0].isalnum() or line[0] == '<'):
                        title = line.rstrip()
                        break
                f.close()
                if title is None:
                    title = os.path.basename(docname)
            self.titles[docname] = title
        return title