fix vertical char spacing for consecutive em dashes #388

                    fm = QFontMetrics(block.charFormat().font())

                else:

                    num_rspaces, num_lspaces, char_yoffset_lst, line_pos = self.line_spaces_lst[blk_no][line.lineNumber()]

                    y = char_yoffset_lst[cpos - line_pos]

                    yidx = cpos - line_pos

                    if yidx >= 0 < len(char_yoffset_lst):

                        y = char_yoffset_lst[yidx]

                painter.setCompositionMode(QPainter.CompositionMode.RasterOp_NotDestination)

                painter.fillRect(QRectF(x, y, fm.height(), 2), painter.pen().brush())

            if not line.isValid():

                break

            if self.force_single_char:

            line.setLineWidth(block_width)

            line.setNumColumns(1)

            else:

                line.setLineWidth(block_width)

            available_height = self.available_height + doc_margin

            text_len = line.textLength()

            tbr_h = space_w = let_sp_offset = 0

            char_idx += num_lspaces

            # https://github.com/dmMaze/BallonsTranslator/issues/388#issuecomment-1975146419

            no_let_sp = set()

            for it in re.finditer('——', blk_text):

                no_let_sp.add(it.start())

            single_char_h = None

            if char_idx < blk_text_len:

                cfmt = self.get_char_fontfmt(block_no, char_idx)

                space_w = cfmt.space_width

                if char_idx in no_let_sp:

                    let_sp_offset = 0

                else:

                let_sp_offset = cfmt.tbr.height() * (ls - 1)

                tbr_h = cfmt.tbr.height() + let_sp_offset

                char = blk_text[char_idx]

                if char in PUNSET_VERNEEDROTATE:

                    tbr, br = cfmt.punc_rect(char)

                    tbr_h = tbr.width()

                    single_char_h = tbr.width()

                    tbr_h = tbr.width() * text_len

                    if char.isalpha():

                        cw2 = cfmt.punc_rect(char+char)[1].width()

                        tbr_h = br.width() - (br.width() * 2 - cw2)

                    if char in {'…', '⋯'}:

                    if char in {'…', '⋯', '—'}:

                        tbr_h = line.naturalTextWidth() - num_lspaces * space_w

                        next_char_idx = char_idx + 1

                        if next_char_idx < blk_text_len and blk_text[next_char_idx] == char:

                shrink_height = max(shrink_height, line_bottom)

            line.setPosition(QPointF(x_offset, line_y_offset))

            if text_len > 1 and single_char_h is not None:

                for ii in range(text_len - 1):

                    blk_char_yoffset.append([line_y_offset + ii * single_char_h, line_y_offset + (ii + 1) * single_char_h])

                blk_char_yoffset.append([blk_char_yoffset[-1][1], line_bottom])

            else:

                blk_char_yoffset.append([line_y_offset, line_bottom])

            line_y_offset = max(line_bottom, doc_margin)

            char_idx += text_len - num_lspaces

        tl.endLayout()