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_simple.rb

@@ -0,0 +1,18 @@
+require_relative "helper"
+
+module Sol
+  class TestSendSimpleSlotMachine < MiniTest::Test
+    include SimpleSendHarness
+
+    def send_method
+      "5.div4;return"
+    end
+    def receiver
+      [SlotMachine::IntegerConstant , 5]
+    end
+    def test_call_has_right_method
+      assert_equal :div4,  @ins.next(2).method.name
+    end
+
+  end
+end