Environment.echo does not need an attr_accessor

lib/rscons/environment.rb

@@ -1,15 +1,14 @@
 module Rscons
   class Environment
-    # Values:
+    # Hash of Builder Name => Builder Class
+    attr_reader :builders
+
+    # possible +options+:
+    #   :echo:
     #     :none - do not print anything
     #     :short - rscons will print a short representation of the step
     #              being performed
     #     :command (default) - print the full command being executed
-    attr_accessor :echo
-
-    # Hash of Builder Name => Builder Class
-    attr_reader :builders
-
     def initialize(options = {})
       @echo = :command
       @variables = options.reject { |key, val| not key[0] =~ /[A-Z]/ }