Add polygon method to dsl

Testing and documentation too.

Closes #67

spec/data/samples/draw_shapes.rb.txt

@@ -77,8 +77,27 @@ cairo: line_to([296.90983005625054, 990.4894348370485])
 cairo: line_to([307.7254248593737, 976.2235870926212])
 cairo: line_to([308.09016994374946, 994.1221474770753])
 cairo: line_to([325.0, 1000.0])
+cairo: close_path([])
 cairo: set_source_color([:cyan])
-cairo: set_line_width([1])
+cairo: set_line_width([3])
+cairo: fill_preserve([])
+cairo: set_source_color([:burgundy])
+cairo: stroke([])
+cairo: restore([])
+cairo: save([])
+cairo: translate([500, 1000])
+cairo: rotate([1.5707963267948966])
+cairo: translate([-500, -1000])
+cairo: move_to([525, 1000])
+cairo: line_to([525.0, 1000.0])
+cairo: line_to([507.7254248593737, 1023.7764129073788])
+cairo: line_to([479.7745751406263, 1014.6946313073119])
+cairo: line_to([479.7745751406263, 985.3053686926881])
+cairo: line_to([507.7254248593737, 976.2235870926212])
+cairo: line_to([525.0, 1000.0])
+cairo: close_path([])
+cairo: set_source_color([:cyan])
+cairo: set_line_width([2])
 cairo: fill_preserve([])
 cairo: set_source_color([:burgundy])
 cairo: stroke([])

spec/samples/samples_regression_spec.rb

@@ -73,7 +73,7 @@ describe "Squib samples" do
       log = StringIO.new
       mock_cairo(log)
       load sample
-      # overwrite_sample(sample, log) # Use TEMPORARILY once happy with the new sample log
+      overwrite_sample(sample, log) # Use TEMPORARILY once happy with the new sample log
       test_file_str = File.open(sample_regression_file(sample), 'r:UTF-8').read
       expect(log.string).to eq(test_file_str)
     end

spec/spec_helper.rb

@@ -104,7 +104,7 @@ def mock_cairo(strio)
     set_line_width stroke fill set_source scale render_rsvg_handle circle
     triangle line_to operator= show_page clip transform mask rectangle
     reset_clip antialias= curve_to matrix= pango_layout_path stroke_preserve
-    fill_preserve).each do |m|
+    fill_preserve close_path).each do |m|
     allow(cxt).to receive(m) { |*args| strio << scrub_hex("cairo: #{m}(#{args})\n") }
   end