Get rid of some unnecessary Haml::Plugin methods.

lib/haml/template/plugin.rb

@@ -10,14 +10,6 @@ module Haml
       1
     end
 
-    def compilable?
-      true
-    end
-
-    def line_offset
-      self.class.line_offset
-    end
-
     def compile(source)
       options = Haml::Template.options.dup
 
@@ -32,10 +24,6 @@ module Haml
         eval("_hamlout.buffer", block.binding)
       end
     end
-
-    def read_template_file(template_path, extension)
-      File.read(template_path)
-    end
   end
 end