explicit tags for all(?) features

[y-ack]

• [x] \b (bold)
• [x] \u (underline)
• [x] \i (italic)
• [x] \s (strikethrough)
• [x] \quote
• [ ] \code
• [ ] \icode
• [ ] \link (allows naming without bare link?)
• [ ] \embed
• [ ] \img (same as \embed)
• [ ] \hr
• [ ] \h1-4 (block) i think table tags would just be too [spoiler text] up and don't bother