Rename Vool Block to Lambda

Making the distinction clearer
Some fixing of previous (wip)

test/ruby/test_ruby_block_statement.rb

@@ -38,7 +38,7 @@ module Ruby
     def test_first
       assert_equal Vool::LocalAssignment , @lst.first.class
       assert @lst.first.name.to_s.start_with?("implicit_block_")
-      assert_equal Vool::BlockStatement , @lst.first.value.class
+      assert_equal Vool::LambdaStatement , @lst.first.value.class
     end
     def test_last_send
       assert_equal 2 , @lst.length

test/ruby/test_ruby_block_statement1.rb

@@ -41,7 +41,7 @@ module Ruby
       assert @lst.first.first.name.to_s.start_with?("implicit_block")
     end
     def test_block_assign_right
-      assert_equal Vool::BlockStatement , @lst.first.first.value.class
+      assert_equal Vool::LambdaStatement , @lst.first.first.value.class
     end
     def test_a_assign
       assert_equal Vool::LocalAssignment , @lst.first.last.class