added font-face mixin with font_files function

lib/compass/frameworks/compass/stylesheets/compass/_css3.sass

@@ -9,3 +9,4 @@
 @import css3/background_clip.sass
 @import css3/background_origin.sass
 @import css3/background_size.sass
+@import css3/font_face.sass

lib/compass/frameworks/compass/stylesheets/compass/css3/_font_face.sass

@@ -0,0 +1,31 @@
+// @Font-Face
+// Cross-browser support for @font-face
+//  - !name is required, arbitrary, and what you will use in font stacks.
+//  - !font_files is required using font_files('relative_location', 'format').
+//     - for best results use this order: woff, opentype/truetype, svg
+//  - !eot is required by IE, and is a relative location of the eot file.
+//  - postscript name is required by some browsers to look for local fonts.
+=font-face( !name, !font_files, !eot = false, !postscript = !false, !style = false)
+  @font-face
+    font-family: '#{!name}'
+    @if !style
+      font-style= !style
+    @if !eot
+      src: url('#{!eot}')
+    @if !postscript
+      src: local('#{!name}'), local('#{!postscript}'), #{!font_files}
+    @else
+      src: local('#{!name}'), #{!font_files}
+
+// EXAMPLE
+  +font-face("this name", font_files("this.otf", "opentype", "this.woff", "woff"), "fonts/this.eot", "thisname")
+  
+  will generate:
+    
+    @font-face { 
+      font-family: 'this name'; 
+      src: url('fonts/this.eot'); 
+      src: local('this name'), local('thisname'), 
+        url('this.otf') format('opentype'), 
+        url('this.woff') format('woff'); 
+    }

lib/compass/sass_extensions/functions.rb

@@ -12,6 +12,7 @@ module Sass::Script::Functions
   include Compass::SassExtensions::Functions::Display
   include Compass::SassExtensions::Functions::InlineImage
   include Compass::SassExtensions::Functions::ColorStop
+  include Compass::SassExtensions::Functions::FontFiles
 end
 
 # Wierd that this has to be re-included to pick up sub-modules. Ruby bug?

lib/compass/sass_extensions/functions/font_files.rb

@@ -0,0 +1,10 @@
+module Compass::SassExtensions::Functions::FontFiles
+  def font_files(*args)
+    raise Sass::SyntaxError, "An even number of arguments must be passed to color-stop()" unless args.size % 2 == 0
+    files = []
+    while args.size > 0
+      files << "url('#{args.shift}') format('#{args.shift}')"
+    end
+    Sass::Script::String.new(files.join(", "))
+  end
+end