[ticket/12983] Correctly validate sorting options in the UCP

PHPBB3-12983
[ticket/13046] Call phpbb_load_extensions_autoloaders() in $download/file.php

PHPBB3-13046
[ticket/13047] Add $post_list array to core.viewtopic_modify_page_title event

PHPBB3-13047
[ticket/13048] Only update session_page if request is not ajax

PHPBB3-13048
Merge pull request #2925 from nickvergessen/ticket/12983

Ticket/12983 UCP preferences, Display posts ordering by: input is not properly validated
Merge pull request #2928 from Nicofuma/ticket/13046

[ticket/13046] Call phpbb_load_extensions_autoloaders() in $download/file.php

* Nicofuma/ticket/13046:
  [ticket/13046] Call phpbb_load_extensions_autoloaders() in $download/file.php
Merge pull request #2929 from rxu/ticket/13047

[ticket/13047] Add $post_list array to core.viewtopic_modify_page_title event

* rxu/ticket/13047:
  [ticket/13047] Add $post_list array to core.viewtopic_modify_page_title event
Merge pull request #2930 from Senky/ticket/13048

[ticket/13048] AJAX requests are being stored to session_page

* Senky/ticket/13048:
  [ticket/13048] Only update session_page if request is not ajax