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

test/sol/send/test_send_args_send.rb

@@ -0,0 +1,27 @@
+require_relative "helper"
+
+module Sol
+  class TestSendArgsSendSlotMachine < MiniTest::Test
+    include SolCompile
+
+    def setup
+      @compiler = compile_main( "a = main(4.div4);return a" , "Integer.div4")
+      @ins = @compiler.slot_instructions.next
+    end
+
+    def test_array
+      check_array [MessageSetup, ArgumentTransfer, SimpleCall, SlotLoad, MessageSetup ,
+                    ArgumentTransfer, SimpleCall, SlotLoad ,SlotLoad, ReturnJump,
+                    Label, ReturnSequence , Label] , @ins
+    end
+
+    def test_one_call
+      assert_equal SimpleCall, @ins.next(2).class
+      assert_equal :div4 , @ins.next(2).method.name
+    end
+    def test_two_call
+      assert_equal SimpleCall, @ins.next(6).class
+      assert_equal :main, @ins.next(6).method.name
+    end
+  end
+end