[ticket/12042] Add all language strings from PLUpload 2.0 to the language file

PHPBB3-12042
[ticket/12042] Replace B with a more meaningful key name

PHPBB3-12042
[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/12042' into develop

# By Joas Schilling
# Via Joas Schilling
* nickvergessen/ticket/12042:
  [ticket/12042] Replace B with a more meaningful key name
  [ticket/12042] Add all language strings from PLUpload 2.0 to the language file
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>
[ticket/12048] Fix the regexp for language keys in custom bbcodes.

PHPBB3-12048
Merge remote-tracking branch 'prototech/ticket/12048' into develop-olympus

* prototech/ticket/12048:
  [ticket/12048] Fix the regexp for language keys in custom bbcodes.
Merge branch 'develop-olympus' into develop

* develop-olympus:
  [ticket/12048] Fix the regexp for language keys in custom bbcodes.