[feature/event-dispatcher] Introduce a port of Symfony2 EventDispatcher

PHPBB3-9550
[feature/event-dispatcher] Allow subscribers to be loaded from extensions

PHPBB3-9550
[feature/event-dispatcher] Add a sample hook in page_header

PHPBB3-9550
[feature/event-dispatcher] Support setting data on an event

PHPBB3-9550
[feature/event-dispatcher] Prefix event name with 'core.'

PHPBB3-9550
[feature/event-dispatcher] Fix event class name in dispatcher interface

PHPBB3-9550
[feature/event-dispatcher] Add Symfony2 to AUTHORS

PHPBB3-9550
[feature/event-dispatcher] Correct copyright statement for Symfony2 files

Also add a notice to the files that were taken from Symfony2.

PHPBB3-9550
[feature/prosilver-cleanup/css-reset-v2] CSS reset

Adding proper CSS reset to prosilver

PHPBB3-10617
[ticket/10684] Send notifications for users with stale bans

PHPBB3-10684
[ticket/10684] Fix 2 typos in comment lines.

PHPBB3-10684
[ticket/10684] Remove isset() for $sql_ignore_users update

PHPBB3-10684
[ticket/10694] Update PHP warning to 5.3.2

PHPBB3-10694
[ticket/10684] Refactor $sql_ignore_users array update

PHPBB3-10684
[ticket/10694] Adjusting details link to 5.3 announcement

PHPBB3-10694
[ticket/10684] Cast user_id to integer

PHPBB3-10684
[feature/event-dispatcher] Remove copied EventDispatcher code

PHPBB3-9550
[feature/event-dispatcher] Use real EventDispatcher through composer

* replace the copy-pasta EventDispatcher with the real one from Symfony2
* use composer for managing this dependency, use composer autoloading

PHPBB3-9550
Merge branch 'develop' into feature/event-dispatcher

* develop: (95 commits)
  [ticket/9084] Explain the logic.
  [ticket/10653] Call get_row_count of base class in mysql get_estimated_row_count
  [ticket/9813] Only get posts table row count if we detected a fulltext index.
  [feature/append_var] Adding test case
  [ticket/7432] Delete redundant reference to "appropriate menu item".
  [ticket/10618] Change phpBB 3 to phpBB 3.1.
  [ticket/10685] Refactor template test defaults for php 5.4 compatibility.
  [feature/append_var] Adding append_var template class function
  [ticket/9813] Also use estimated row count of posts table for fulltext mysql.
  [ticket/10653] Fix parameter to substr() in unit tests. Should be 1, not -1.
  [ticket/10653] Unit tests for get_row_count() and get_estimated_row_count().
  [ticket/10653] Add ability to count table rows to database abstraction layer.
  [ticket/9813] Use table status row count only if greater than 100000 or exact.
  [ticket/9813] Use SHOW TABLE STATUS to get search stats for native on MySQL.
  [ticket/8652] Comment for also updating forum watch table in user_notification.
  [ticket/8652] Sending 2 emails on 2 replies
  [ticket/10680] Add /phpBB/ext/* to .gitignore
  [ticket/10672] Fix total post count language string in statistics and feed
  [ticket/9220] Remove margin on table.table1 so it's centered in the blue box.
  [ticket/10453] Fixing spacing
  ...

Conflicts:
	tests/bootstrap.php
[ticket/10684] Adjust pm_notifications() to handle stale bans

- Add parameter (array) to the function phpbb_get_banned_users_ids()
- Fix function pm_notification() to handle users with stale bans

PHPBB3-10684