Rename Vool to Sol

Simple is really the descriptive name for the layer
Sure, it is "virtual" but that is not as important as the fact that it is simple (or simplified)
Also objct (based really) is better, since orientated implies it is a little like that, but only orientated, not really it. Sol only has objects, nothing else
Just cause i was renaming anyway

lib/sol/variables.rb

@@ -0,0 +1,67 @@
+module Sol
+  module Named
+    attr_reader :name
+    def initialize name
+      @name = name
+    end
+    def each(&block)
+    end
+  end
+
+  class LocalVariable < Expression
+    include Named
+    def to_slot_definition(compiler)
+      slot_def = compiler.slot_type_for(@name)
+      SlotMachine::SlotDefinition.new(:message , slot_def)
+    end
+    def to_s(depth = 0)
+      name.to_s
+    end
+    def each(&block)
+      block.call(self)
+    end
+  end
+
+  class InstanceVariable < Expression
+    include Named
+    def to_slot_definition(_)
+      SlotMachine::SlotDefinition.new(:message , [ :receiver , @name] )
+    end
+    # used to collect type information
+    def add_ivar( array )
+      array << @name
+    end
+    def to_s(depth = 0)
+      at_depth(depth , "@#{name}")
+    end
+    def each(&block)
+      block.call(self)
+    end
+  end
+
+  class ClassVariable < Expression
+    include Named
+    def each(&block)
+      block.call(self)
+    end
+  end
+
+  class ModuleName < Expression
+    include Named
+    def ct_type
+      get_named_class.single_class.instance_type
+    end
+    def to_slot_definition(_)
+      return SlotMachine::SlotDefinition.new( get_named_class, [])
+    end
+    def get_named_class
+      Parfait.object_space.get_class_by_name(self.name)
+    end
+    def each(&block)
+      block.call(self)
+    end
+    def to_s
+      @name.to_s
+    end
+  end
+end