Copied from the INCLUDECSS PR, since this needed to be modified.
Added checks for argument strings/anchors/http/https paths in asset files
to load files properly
PHPBB3-11388
If debug mode is enabled, lets check for new/removed EVENT templates on
page load rather than at compile. This is slower, but makes developing
extensions easier (no need to purge the cache when a new event template
file is added)
PHPBB3-11598
Now we can do {L_TITLE|upper}, {SITENAME|lower}, etc
We can also use all the Twig tags in our own syntax. E.g. <!-- BLOCK foo -->
= {% block foo %]. All tags are the same as the Twig tag names, but are
in uppercase.
PHPBB3-11598
set_style now accepts an array containing a list of paths, e.g. array(
'ext/foo/bar/styles', 'styles'). Default: array('styles')
Using this option allows us to set the style based on the user's preferred
style (including the full tree), but use one or more base directories to
add the paths from.
The main use for this ability is so that extensions can call set_style,
including their path and the phpBB styles path (or any others) and have
their template files loaded from those directories (in the order given).
PHPBB3-11598
We output some language vars to the context (e.g. L_TITLE in the ACP). These
do not exist in user->lang, so we must check the context vars first, if not
in context, we output the result of user->lang.
PHPBB3-11598
As a last resort, now we use the Twig Loader to find the correct file to
include to (most specific file first, then parent styles). Also allows
using @namespace convention. This is ONLY done if the specified path is not
an absolute path AND the file does not exist relative to the phpBB root path.
PHPBB3-11598
This was done because T_TEMPLATE_PATH is not always correct for js files
(e.g. the inheriting style does not include these). Now we use the Twig
Loader to find the correct file to link to (most specific file first, then
parent styles). Also allows using @namespace convention
PHPBB3-11598
This had to be done because, like DEFINE, setting variables to $context
only affected the local file and any children, not parent templates.
PHPBB3-11598
