[feature/plupload/deps] Adding parts of plupload_1_5_7.zip

PHPBB3-10929
[feature/plupload/deps] Add information about Plupload to AUTHORS.

PHPBB3-10929
[ticket/11621] Remove mysql extra indexes

Remove post_text index as post_content index is sufficient to search post
text.

PHPBB3-11621
Merge remote-tracking branch 'phpbb/develop' into ticket/11621

* phpbb/develop: (542 commits)
  [ticket/11901] Pass empty string as relative_url for non-local magic URL.
  [ticket/11898] Correct adm_relative_path created by installer
  [ticket/11898] Correct admin S_LOGIN_ACTION
  [ticket/11892] Fix undefined variables: to_forum_id & to_topic_id
  [ticket/11890] Fix untranslated string when deleting posts through MCP.
  [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
  [ticket/11888] Update default search backend in namespaces migration
  [ticket/11739] Rename “Remember Me” login keys module
  [ticket/11893] Remove unnecessary <fieldset> causing a large font size
  [ticket/11894] Fix typo in "Delete post" option
  [ticket/11888] Use \phpbb\search\fulltext_native as search backend config
  [ticket/11608] Mark failed test as incomplete for mysql search backend
  [ticket/11608] Update search backend class names to namespaces
  [ticket/11608] Move markIncomplete to search backends test
  [ticket/11608] Rename base search test class file
  [ticket/11608] Remove suffix test from base class
  [ticket/11608] Mark postgres search not found test as incomplete
  ...
[ticket/11621] Swap columns of post_content index.

PHPBB3-11621
[ticket/11621] Remove unnecessary things around index_created() return value.

PHPBB3-11621
[ticket/11621] Add migration dropping MySQL search indexes.

Possibly time-consuming index-regeneration will be left to the user.

PHPBB3-11621
[ticket/11905] 3.1.0-a1 Migration

Created a migration tips develop tool to help find the migration tree tips so
they can be copied to versions released.

With this, A1 is the only current tree tip (it depends on all other migrations).

PHPBB3-11905
Merge pull request #1767 from EXreaction/ticket/11905

[ticket/11905] 3.1.0-a1 Migration
[ticket/11906] Add missing configs from notifications cron to schema_data.sql

PHPBB3-11906
[ticket/11906] Add notification purge cron to cron tasks

PHPBB3-11906
[ticket/11867] Schema files are not created by create_schema_files.php

PHPBB3-11867
Merge remote-tracking branch 'nickvergessen/ticket/11867' into develop

# By Joas Schilling
# Via Joas Schilling
* nickvergessen/ticket/11867:
  [ticket/11867] Schema files are not created by create_schema_files.php
[ticket/11906] Fix namespace issues in prune_notifications

PHPBB3-11906
[ticket/11621] Use effectively_installed() instead.

PHPBB3-11621
Merge remote-tracking branch 'phpbb/develop' into ticket/11621

* phpbb/develop:
  [ticket/11867] Schema files are not created by create_schema_files.php
  [ticket/11905] 3.1.0-a1 Migration
  [ticket/11903] Speed up paging test
  [ticket/11703] Extend the correct migration class.
  [ticket/11874] Correct when $phpbb_root_path is appended to build_url()
  [ticket/11703] Also use empty() for T_JQUERY_LINK.
  [ticket/11703] Add effectively_installed().
  [ticket/11703] Make jQuery CDN switch more generic.
  [ticket/11874] Fix tests
  [ticket/11874] Do not always prepend the web path; only replace phpbb_root_path
  [ticket/11345] Don't include scheme, so HTTPS is used where necessary.
  [ticket/11345] Wrap remote webfonts in S_ALLOW_CDN.
  [ticket/11345] Move css import to template
  [ticket/11345] Add Droid Sans as fallback font
  [ticket/11345] Change font for buttons
[ticket/11621] Put mysql_fulltext_drop into alpha1 migration.

PHPBB3-11621
Merge remote-tracking branch 'nickvergessen/ticket/11906' into develop

# By Joas Schilling
# Via Joas Schilling
* nickvergessen/ticket/11906:
  [ticket/11906] Fix namespace issues in prune_notifications
  [ticket/11906] Add notification purge cron to cron tasks
  [ticket/11906] Add missing configs from notifications cron to schema_data.sql
[ticket/11908] Namespacify phpbb_auth_provider_oauth_service_exception.

PHPBB3-11908
[feature/plupload/cron] Add cronjob for cleaning plupload temporary directory.

PHPBB3-10929