Execution order matters: if plugin A depends on plugin B, it usually means that plugin B does stuff which plugin A requires. However, Pico loads plugins in alphabetical order, so events might get fired on plugin A before plugin B.
Hence plugins need to be sorted. Pico sorts plugins using a dependency topology, this means that it moves all plugins, on which a plugin depends, in front of that plugin. The order isn't touched apart from that, so they are still sorted alphabetically, as long as this doesn't interfere with the dependency topology. Circular dependencies are being ignored; their behavior is undefiend. Missing dependencies are being ignored until you try to enable the dependant plugin.
This method bases on [Marc J. Schmidt's Topological Sort library](https://github.com/marcj/topsort.php) in version 1.1.0, licensed under the MIT license. It uses the `ArraySort` implementation ([class `\MJS\TopSort\Implementations\ArraySort`](https://github.com/marcj/topsort.php/blob/1.1.0/src/Implementations/ArraySort.php)).
This method can be used to validate and filter input data and can be called via `Pico::getUrlParameter()` (URL GET parameters) and `Pico::getFormParameter()` (HTTP POST parameters). `Pico::filterVariable()` is basically a wrapper for PHP's `filter_var()` function with various compatibility extensions to allow theme developers to use its functionality in Twig templates. Therefore Pico 1.1 adds the `url_param` (`Pico::getUrlParameter()`) and `form_param` (`Pico::getFormParameter()`) Twig functions.
Resolves#305
\Symfony\Component\Yaml\Parser::parse() returns the unchanged value when a 1-liner string which is no valid YAML is passed. Assume this string to be the page title. Thus the following page will work now:
```
---
This is the title
---
# Example page
{{ meta.title }} is going to be "This is the title" - or "%meta.title%" == "This is the title".
```
This allows one to prevent Pico from removing the last "index" path component. Example use case: Pico's official admin plugin. We must distinguish between "content/sub.md" and "content/sub/index.md", otherwise it wouldn't be possible to edit both pages.
With Pico 1.0 you had to setup URL rewriting (e.g. using `mod_rewrite` on Apache) in a way that rewritten URLs follow the `QUERY_STRING` principles. Starting with version 1.1, Pico additionally supports the `REQUEST_URI` routing method, what allows you to simply rewrite all requests to just `index.php`. Pico then reads the requested page from the `REQUEST_URI` environment variable provided by the webserver. Please note that `QUERY_STRING` takes precedence over `REQUEST_URI`.
Symfony YAML interprets ISO-8601 datetime strings and returns timestamps instead of the string. This behavior conforms to the YAML standard, i.e. this is no bug of Symfony YAML.
Fixes#336. Thanks @csholmq for reporting this.
Resolves#330
After loading the `config/config.php`, Pico proceeds with any existing `config/*.config.php` in alphabetical order. The file order is crucial: Config values which has been set already, cannot be overwritten by a succeeding file. This is also true for arrays, i.e. when specifying `$config['test'] = array('foo' => 'bar')` in `config/a.config.php` and `$config['test'] = array('baz' => 42)` in `config/b.config.php`, `$config['test']['baz']` will be undefined
