Allow process timeouts to be specified for Yui

- provide a setTimeout method to specify the timeout that the process can run for (currently hardcoded to 60 seconds)
- provide a means that this can be applied to other filters which use the ProcessBuilder
Merge remote branch 'upstream/master'
Add a simple array cache to a provide a consistent interface for non-persistant caches
Modify regex in filterIEFilters()

Changed (?<url>) in regex to (?P<url>) because the short version is not supported in PCRE lower than 7.0 such as in CentOS 5.8.
Merge pull request #319 from Kaivosukeltaja/patch-1

Modify regex in filterIEFilters()
Update README.md

Tiny type
Merge pull request #323 from loalf/patch-1

Typo
Added filter for Dart
Merge pull request #318 from SamsonIT/master

Added way to add import paths to scssphp parser
Assetic Issue #248

https://github.com/kriswallsmith/assetic/issues/248
fonts_dir as config entry, not command line param
Merge pull request #317 from xzyfer/feature/controller/asset-cache

Add a non-persistant asset cache
Merge pull request #329 from shql/master

Added support for compass fonts_dir config entry
Fixed the tests for the Twig extension
Made the initialization of variable values lazy

This avoids calling the supplier if you don't have any asset using
variables.
It also fixes symfony/AsseticBundle#138 as the supplier is not called
anymore as soon as the Twig globals are read from the extension.
Merge pull request #332 from stof/lazy_value_retrieving

Made the initialization of variable values lazy
added missing test group
Merge pull request #277 from steveybaby2/master

[Filters] Fixed issue with Yui process timing out by providing a setTimeout function
In LessphpFilter, allow formatter to be changed.
In LessphpFilter, allow comments to be preserved in the output.