Explicitly specify fonts directory

Fixes a bug where the fonts directory was specified in the compass configuration. The compass configuration assumes assumes the directory is a  relative path from the specified project path (currently `sys_get_temp_dir()`).
Compass filter: added support for --relative-assets option
css cache busting filter
Copied code for the compass asset dependencies detection (PR #362) from the SassFilter Class.
Methods copied: getChildren, partialize
Added compress options for UglifyJS
add function to set variables in scss parser
Update ScssPhpFilter.php

Class replacement for new ScssPhp structure
Merge remote-tracking branch 'upstream/master'
add minifycsscompressor filter

fix license and class phpdoc
fixed autoprefixer unit tests introduced in #472
updated asserts
Allow custom functions to be registered on the Lessphp filter.
Merge pull request #644 from mente/autoprefix-path

fixed autoprefixer unit tests problem introduced in #472
Fixed the autoprefixer test
Merge pull request #487 from hjr3/fonts_dir

Explicitly specify compass fonts directory
Merge remote-tracking branch 'origin/pull/640/head'
added BaseSassFilter
Merge pull request #647 from mikeyclarke/lessphp-functions

Allow custom functions to be registered on the Lessphp filter.
allow functions.php to be included many times

apparently laravel workbench requires this
fixes #636
see #649
Merge pull request #641 from dominikzogg/minifycsscompressor

add minifycsscompressor filter