[feature/migrations] Store depends on in the database (serialized)

This is required so that when migrations are reverted we can check through
all installed migrations and make sure that all dependencies are handled
properly and so that we are only required to load the migrations files
that could be dependent on the ones installed.

I believe in normal proper use the old way might have worked, but in case
something happens and an unrelated migration file is installed, but cannot
be loaded, this makes sure we do not stop everything unless we absolutely
must (one of those files is dependent on something we want to revert).

PHPBB3-9737
[feature/migrations] Move test.php -> install/database_update_migrations.php

This should be used as a basis for the database updater using migrations.

PHPBB3-9737
[feature/migrations] install/database_update_migrations.php

Actually, this does not belong in the main PR, moving to the data PR.

PHPBB3-9737
[ticket/11320] Include functions file as we need phpbb_convert_30_dbms_to_31

PHPBB3-11320
[feature/migrations] Make depends_on static to call it without dependencies

PHPBB3-11318
[feature/migrations] Make the test depends_on methods static

PHPBB3-11318
[ticket/11321] Recreate schema files with develop/create_schema_files.php

PHPBB3-11321
Merge remote-tracking branch 'nickvergessen/ticket/11321' into develop

* nickvergessen/ticket/11321:
  [ticket/11321] Recreate schema files with develop/create_schema_files.php
[ticket/11201] Remove MSN/WLM fields

WLM will be shutdown in March 2013. Skype is the new replacement. But as Skype
uses a different login ID and service, the values in this field are useless.
So we can safely remove the field and the links/functions we create.

PHPBB3-11201
[ticket/11314] Fix whitespace issues

PHPBB3-11314
[feature/migrations] Make load_migrations recursive (optionally)

PHPBB3-9737
[feature/migrations] Function effectively_installed() in migrations

Allows you to check if the migration is effectively installed
(entirely optionall)

This function is intended to help moving to migrations from a
previous database updater, where some migrations may have been
installed already even though they are not yet listed in the
migrations table.

PHPBB3-9737
[feature/migrations] Function to populate the migrations table (for install)

PHPBB3-9737
[feature/migrations] Make sure migration data not done before running data step

PHPBB3-9737
[ticket/11314] Add missing radix parameters

PHPBB3-11314
[ticket/11324] Add PHP 5.5 environment to travis and allow it to fail.

PHPBB3-11324
Merge remote-tracking branch 'EXreaction/ticket/11320' into develop

* EXreaction/ticket/11320:
  [ticket/11320] Include functions file as we need phpbb_convert_30_dbms_to_31
Merge PR #1191 branch 'bantu/ticket/11324' into develop-olympus

# By Andreas Fischer
# Via Andreas Fischer
* bantu/ticket/11324:
  [ticket/11324] Add PHP 5.5 environment to travis and allow it to fail.
Merge PR #1191 branch 'develop-olympus' into develop

# By Andreas Fischer
# Via Andreas Fischer (1) and Oleg Pudeyev (1)
* develop-olympus:
  [ticket/11324] Add PHP 5.5 environment to travis and allow it to fail.
[ticket/11323] Backport include_define test to olympus.

PHPBB3-11323