[ticket/10383] AJAXify poll voting

PHPBB3-10383
[ticket/10383] Make the content transitions smoother.

PHPBB3-10383
[ticket/10383] Update the results without the overlay popup.

PHPBB3-10383
Merge pull request #1757 from prototech/ticket/10383

[ticket/10383] AJAXify poll voting
[ticket/11895] Fix undefined $forum_id

PHPBB3-11895
Merge remote-tracking branch 'EXreaction/ticket/11895' into develop

* EXreaction/ticket/11895:
  [ticket/11895] Fix undefined $forum_id
Merge remote-tracking branch 'phpbb-core/develop'

* phpbb-core/develop:
  [ticket/11895] Fix undefined $forum_id
  [ticket/10383] Update the results without the overlay popup.
  [ticket/10383] Make the content transitions smoother.
  [ticket/10383] AJAXify poll voting