rework resolve_method, using builder

lib/mom/instruction/message_setup.rb

@@ -27,8 +27,7 @@ module Mom
     # Move method name, frame and arguemnt types from the method to the next_message
     # Get the message from Space and link it.
     def to_risc(compiler)
-      builder = Risc::Builder.new(compiler)
-      build_with(builder)
+      build_with(compiler.builder)
     end
 
     # directly called by to_risc

lib/mom/instruction/slot_load.rb

@@ -1,6 +1,6 @@
 module Mom
 
-  # SlotLoad is an abstract base class for moving data into a slot
+  # SlotLoad is for moving data into a slot, either from another slot, or constant
   # A Slot is basically an instance variable, but it must be of known type
   #
   # The value loaded (the right hand side) can be a constant (Mom::Constant) or come from