split compilers resolve_type into the three possibilities

cleaner code, though temporary it shifts some dirt
into the index method. up next

lib/vool/send_statement.rb

@@ -72,7 +72,7 @@ module Vool
     # - Setting up the next message, with receiver, arguments, and (importantly) return address
     # - a CachedCall , or a SimpleCall, depending on wether the receiver type can be determined
     def to_mom( compiler )
-      @receiver = SelfExpression.new(compiler.resolve_type(:receiver)) if @receiver.is_a?(SelfExpression)
+      @receiver = SelfExpression.new(compiler.receiver_type) if @receiver.is_a?(SelfExpression)
       if(@receiver.ct_type)
         simple_call(compiler)
       else