2.7.0

• new TbConfiguration.newInstanceFrameless() preset: no box-frame around the content, left aligned - like a personally written email (great for invitations or signature-style emails)
• new content.align config (center/left) to control the placement of the content-block
• new preheader(...) builder option: hidden preview-text shown by email-clients in the inbox-list
• fixed responsive behaviour: email now correctly collapses to full width below 600px viewport
• upgraded dependencies (pebble 4.1.2, commonmark 0.29.0, junit 5.14.4, lombok 1.18.46)
• smaller cleanups and fixes