rename risc_value to register_value

almost to register, but it still carries that value

lib/risc/instructions/setter.rb

@@ -22,9 +22,9 @@ module Risc
       @array = array
       @index = index
 #      raise "index 0 " if index < 0
-      raise "Not integer or reg #{index}" unless index.is_a?(Numeric) or RiscValue.look_like_reg(index)
-      raise "Not register #{register}" unless RiscValue.look_like_reg(register)
-      raise "Not register #{array}" unless RiscValue.look_like_reg(array)
+      raise "Not integer or reg #{index}" unless index.is_a?(Numeric) or RegisterValue.look_like_reg(index)
+      raise "Not register #{register}" unless RegisterValue.look_like_reg(register)
+      raise "Not register #{array}" unless RegisterValue.look_like_reg(array)
     end
     attr_accessor :register , :array , :index