[ticket/11445] Optimize no of queries in get_global_subscriptions

PHPBB3-11445
[ticket/11445] Improve unit tests for get_global_subscriptions

PHPBB3-11445
[ticket/11445] Remove unused foreach key $group_name

PHPBB3-11445
[ticket/11445] Move get user's notification code into its own method

PHPBB3-11445
[ticket/12687] Add a constant to display the load time without DEBUG

PHPBB3-12687
[ticket/12687] Display the explain link only when DEBUG is set

PHPBB3-12687
[ticket/12687] Rename DISPLAY_LOAD_TIME to PHPBB_DISPLAY_LOAD_TIME

PHPBB3-12687
[ticket/12687] Return a string and move the displaying of the sql report

PHPBB3-12687
[ticket/12687] Remove globals

PHPBB3-12687
[ticket/12687] Use microtime(true)

PHPBB3-12687
[ticket/12687] Update doc block

PHPBB3-12687
[ticket/12487] Use new `microtime()` parameter
[ticket/12697] Delete cached extension schema.json files after testing

PHPBB3-12697
[ticket/12687] Fix the namespace of $request

PHPBB3-12687
Merge pull request #2580 from VSEphpbb/ticket/12697

[ticket/12697] Delete cached extension schema.json files after testing

* VSEphpbb/ticket/12697:
  [ticket/12697] Delete cached extension schema.json files after testing
[ticket/12682] Make Code Sniffer run properly on Travis CI again.

The --ignore parameter takes a case-insensitive pattern and as such
'phpBB/phpbb/*' matches any '/home/travis/build/phpbb/phpbb/...' file name.
This results in nothing being checked against ruleset-php-legacy.xml.

Using absolute paths in the --ignore pattern fixes this issues.

PHPBB3-12682
[ticket/12209] Notify the admin that OAuth still allows DB authentification

PHPBB3-12209
[ticket/12687] Wrap $GLOBALS['starttime'] in a if

PHPBB3-12687
[ticket/12687] Don't check if memory_get_peak_usage() exists

PHPBB3-12687
[ticket/12687] Display the number of cached queries

PHPBB3-12687