[ticket/11899] Give indication of activity after voting in poll.

PHPBB3-11899
[ticket/11935] Fix <p> tags not allowed inside <strong> tags

PHPBB3-11935
[ticket/11935] Fix incorrect alt tags that should be title tags

PHPBB3-11935
[ticket/11935] Fix stray </a> tags

PHPBB3-11935
[ticket/11935] Fix invalid HTML usage of <label> tag in prosilver

PHPBB3-11935
[ticket/11935] Remove obsolete table attributes from Prosilver

cellpadding, cellspacing, border are obsolete table attributes.
They are handled by CSS already using table and .table1

PHPBB3-11935
[ticket/11935] Replace obsolete table attributes in Admin with CSS

PHPBB3-11935
[ticket/11935] Tweak colour swatch table

PHPBB3-11935
Merge branch 'develop' into ticket/11935
[ticket/11534] Check remote avatar content type if possible

This should make sure that error pages like 404 or 503 pages are not treated
as remote avatar images.

PHPBB3-11534
[ticket/11973] Remove logic from tokens language array

Previously if a translator did no translate a token, it would not be
displayed. On the other hand, the translator could add additional tokens
which have no functionality.  Functionality is already hardcoded into
bbcode.php so we can that in the ACP aswell, in order to prevent namend
issues.

PHPBB3-11973
[ticket/11928] Replace AJAX loading popup with animation.

PHPBB3-11928
[ticket/11928] Make sure the indicator is on top of other elements.

PHPBB3-11928
[ticket/11935] Merge remote-tracking branch 'upstream/develop'

PHPBB3-11935
[ticket/11928] Rename loadingAlert to loading_indicator.

PHPBB3-11928
[ticket/11975] Add ACP link next to MCP link in header

PHPBB3-11975
[ticket/11975] Make link text shorter on smaller resolutions

PHPBB3-11975
[ticket/11975] Change shortened ACP/MCP label to Administer/Moderate

Also utilizing the new data-responsive-text attribute

PHPBB3-11975
[ticket/11975] Remove copy/paste fail, fix tests

PHPBB3-11975
[ticket/11998] Add symfony/console as dependency.

PHPBB3-11998