Profile liquid rendering

Add a simple profiling system to liquid rendering. Each
liquid tag ({{ }} and {% %}) is processed through this profiling,
keeping track of the partial name (in the case of {% include %}), line
number, and the time it took to render the tag. In the case of {%
include %}, the profiler keeps track of the name of the partial and
properly links back tag rendering to the partial and line number for
easy lookup and dive down. With this, it's now possible to track down
exactly how long each tag takes to render.

These hooks get installed and uninstalled on an as-need basis so by
default there is no impact on the overall liquid execution speed.

test/unit/tag_unit_test.rb

@@ -8,4 +8,9 @@ class TagUnitTest < Minitest::Test
     assert_equal 'liquid::tag', tag.name
     assert_equal '', tag.render(Context.new)
   end
+
+  def test_return_raw_text_of_tag
+    tag = Tag.parse("long_tag", "param1, param2, param3", [], {})
+    assert_equal("long_tag param1, param2, param3", tag.raw)
+  end
 end

test/unit/tokenizer_unit_test.rb

@@ -21,6 +21,15 @@ class TokenizerTest < Minitest::Test
     assert_equal ['  ', '{% comment %}', ' ', '{% endcomment %}', ' '], tokenize("  {% comment %} {% endcomment %} ")
   end
 
+  def test_calculate_line_numbers_per_token_with_profiling
+    template = Liquid::Template.parse("", :profile => true)
+
+    assert_equal [1],       template.send(:tokenize, "{{funk}}").map(&:line_number)
+    assert_equal [1, 1, 1], template.send(:tokenize, " {{funk}} ").map(&:line_number)
+    assert_equal [1, 2, 2], template.send(:tokenize, "\n{{funk}}\n").map(&:line_number)
+    assert_equal [1, 1, 3], template.send(:tokenize, " {{\n funk \n}} ").map(&:line_number)
+  end
+
   private
 
   def tokenize(source)

test/unit/variable_unit_test.rb

@@ -133,4 +133,9 @@ class VariableUnitTest < Minitest::Test
       end
     end
   end
+
+  def test_output_raw_source_of_variable
+    var = Variable.new(%! name_of_variable | upcase !)
+    assert_equal " name_of_variable | upcase ", var.raw
+  end
 end