[ticket/12615] Fixed inproper clearing of .topic-actions

PHPBB3-12615
[ticket/12541] Activate attachments tab when files are dropped into textarea

PHPBB3-12541
[ticket/12565] Empty anchors introduce white-space in IE11

PHPBB3-12565
[ticket/12521] Fix MCP merge topics row overflow

PHPBB3-12521
Merge pull request #2536 from PayBas/ticket/12521

[ticket/12521] Fix MCP merge topics row overflow
Merge remote-tracking branch 'PayBas/ticket/12565' into develop-ascraeus

* PayBas/ticket/12565:
  [ticket/12565] Empty anchors introduce white-space in IE11
Merge remote-tracking branch 'PayBas/ticket/12615' into develop-ascraeus

* PayBas/ticket/12615:
  [ticket/12615] Fixed inproper clearing of .topic-actions
Merge remote-tracking branch 'PayBas/ticket/12541' into develop-ascraeus

* PayBas/ticket/12541:
  [ticket/12541] Activate attachments tab when files are dropped into textarea

Conflicts:
	phpBB/styles/prosilver/template/forum_fn.js
[ticket/12666] Use "None" for images in root of gallery avatar path

"None" serves no real purpose right now. After this it will be used instead
of "Main" for images in the root of the gallery avatar path.

PHPBB3-12666
Merge pull request #2552 from marc1706/ticket/12666

[ticket/12666] Use "None" for images in root of gallery avatar path

* marc1706/ticket/12666:
  [ticket/12666] Use "None" for images in root of gallery avatar path