Add compatibility with edge Rails. Thanks to Russell Norris for the patch.

git-svn-id: svn://hamptoncatlin.com/haml/trunk@728 7063305b-7217-0410-af8c-cdc13e5119b9

lib/haml/template/plugin.rb

@@ -8,6 +8,18 @@ module Haml
       1
     end
 
+    def self.compilable?
+      true
+    end
+   
+    def compilable?
+      self.class.compilable?
+    end
+ 
+    def line_offset
+      self.class.line_offset
+    end
+
     def initialize(view)
       @view = view
     end