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/assignment.rb

@@ -0,0 +1,42 @@
+module Sol
+
+  # Base class for assignments (local/ivar), works just as you'd expect
+  # Only "quirk" maybe, that arguments are like locals
+  #
+  # Only actual functionality here is the compile_assign_call which compiles
+  # the call, should the assigned value be a call.
+  class Assignment < Statement
+    attr_reader :name , :value
+    def initialize(name , value )
+      raise "Name nil #{self}" unless name
+      raise "Value nil #{self}" unless value
+      raise "Value cant be Assignment #{value}" if value.is_a?(Assignment)
+      raise "Value cant be Statements #{value}" if value.is_a?(Statements)
+      @name , @value = name , value
+    end
+
+    def each(&block)
+      block.call(self)
+      @value.each(&block)
+    end
+
+    def to_s(depth = 0)
+      at_depth(depth , "#{@name} = #{@value}")
+    end
+
+    # The assign instruction (a slot_load) is produced by delegating the slot to derived
+    # class
+    #
+    # When the right hand side is a CallStatement, it must be compiled, before the assign
+    # is executed
+    #
+    # Derived classes do not implement to_slot, only slot_position
+    def to_slot(compiler)
+      to = SlotMachine::SlotDefinition.new(:message , self.slot_position(compiler))
+      from = @value.to_slot_definition(compiler)
+      assign = SlotMachine::SlotLoad.new(self,to,from)
+      return assign unless @value.is_a?(CallStatement)
+      @value.to_slot(compiler) << assign
+    end
+  end
+end