- Fix notices on PHP 7.4 (Thanks @tomjn, @stronk7, and @JoyceBabu!)

- Fix a parse error in the delimiter change tag (e.g. `{{=<% %>=}}`) and throw a syntax error when it's invalid.
- Improve Tokenizer::scan performance by 98.2%.
- Test against all the PHPs in CI.

* Prevent redundant Autoloader registration (Thanks @hcpss-banderson!)

* Add a ProductionFilesystemLoader, which doesn't read template file contents before every render.
* Improve test coverage.
* Fix a bug when rendering the same block names multiple times in one template.
* Add a `delimiters` option for overriding default delimiters at the engine level.
* Add validation to prevent empty `template_class_prefix` config.

 * Fix test bootstrap in PHP < 5.5

 * Add support for exception chaining (Thanks @thewilkybarkid!)

 * Support parent tags and block args as direct children of blocks and sections.
 * Add support for non-local templates via FilesystemLoader (Thanks @oschettler!)

 * Respect delimiter changes inside lambda sections.

 * Fix incorrect padding added to lambda values inside partials.
 * Make LambdaHelper invokable.

 * Lazily evaluate template BLOCKS pragma sections. See bobthecow#264 …

…and bobthecow#265. Thanks @damyon!

 * Add ANCHORED-DOT pragma to enable "anchored dot notation". See bobthecow#129 and mustache/spec#52
 * A bit of CS cleanup, and remove the unused create_example script.

 * Tons of CS fixes. Thanks @keradus!

 * Fix for extra indent inside template inheritance sections.

 * Add template inheritance, via BLOCKS pragma. Thanks @jazzdan and t…

…he rest of the @etsy devs!

 * Add a `pragmas` option to the Mustache_Engine constructor for enabling default pragmas.
 * A couple of performance improvements. Thanks @nizsheanez!
 * Code cleanup. Thanks @keradus!
 * Check coding standards on CI. Thanks @keradus!
 * Fix whitespace bug in nested partials. Thanks for the bug report, @mikesherov and @behance!
 * Allow omitting the filters on closing section tags, for example, `{{# a | b }}{{/ a }}` is now valid.
 * Increase test coverage, improve comments and examples.

Merge branch 'release/2.6.1'

 * Code cleanup (thanks @keradus!)

 * Fix parse error with mismatched triple-mustache delimiters (thanks @smarden1!)