[ticket/11994] Fix functional tests

PHPBB3-11994
Merge pull request #1845 from nickvergessen/ticket/11994

[ticket/11994] Make extension manager UI less misleading
[ticket/12002] Add link hash to extension manager links

PHPBB3-12002
[ticket/12002] Change functional test to use link hash

PHPBB3-12002
[ticket/12001] Ensure that form data is sent to server in AJAX requests.

PHPBB3-12001
[ticket/11922] Drop all keys before trying to delete columns to avoid issues

On MSSQL columns that have an index can not be dropped.

PHPBB3-11922
[ticket/12007] Default last_result to 0 instead of false

PostgreSQL does not map null/false to 0 and thus this variable causes
an error.

PHPBB3-12007
[ticket/12005] Remove PM popup setting from user preferences
PHPBB3-12005
[ticket/12005] Remove PM popup from converter
PHPBB3-12005
[ticket/12005] Remove PM popup UCP module
PHPBB3-12005
[ticket/12005] Remove PM popup
PHPBB3-12005
[ticket/12005] Remove language vars used by PM popup
PHPBB3-12005
[ticket/12005] Delete templates files
PHPBB3-12005
[ticket/12005] Remove PM popup module from DB
PHPBB3-12005
[ticket/11997] Correctly redirect to front controllers

We currently do a lot of checks in order to prevent users from getting to
a 404 page. However, this logic relies on checking if a file or folder exists.
Due to the front controllers and the URL rewriting in 3.1, it is no longer
possible to rely on existing files for redirecting. This patch will take
care of properly redirecting users to front controller files. An incorrect
link will cause users to get a 404 error though.

PHPBB3-11997
[ticket/11943] Require stricter DEFINE statements for templates

PHPBB3-11943
[ticket/12010] Make the navbar icons clickable.

PHPBB3-12010
[ticket/11943] Split fix_inline_variable_tokens into 3 steps

DEFINE shouldn't add/remove surrounding quotes, but must have the inline
variable tokens fixed

PHPBB3-11943
Merge pull request #1857 from nickvergessen/ticket/11922

[ticket/11922] Drop all keys before trying to delete columns to avoid issues
Merge remote-tracking branch 'dhruv/ticket/12007' into develop

* dhruv/ticket/12007:
  [ticket/12007] Default last_result to 0 instead of false