[ticket/12045] Correctly close <dd> with </dd>

PHPBB3-12045
[ticket/12045] Correctly close <span> before closing parent tag

PHPBB3-12045
[ticket/12045] Only display group selection if there are groups

Also fixed the empty option which is not allowed.

PHPBB3-12045
Merge remote-tracking branch 'nickvergessen/ticket/12045' into develop

# By Joas Schilling
# Via Joas Schilling
* nickvergessen/ticket/12045:
  [ticket/12045] Only display group selection if there are groups
  [ticket/12045] Correctly close <span> before closing parent tag
  [ticket/12045] Correctly close <dd> with </dd>