Added support for merging multiple layout files

samples/custom-layout.yml

@@ -1,3 +1,4 @@
+# Used in the layouts.rb sample in conjunction with custom-layout2.yml
 frame:
   x: 38
   y: 38

samples/custom-layout2.yml

@@ -0,0 +1,15 @@
+# Used in the layouts.rb sample in conjunction with custom-layout.yml
+#
+# When used with custom-layout.yml loaded first, this layout overrides subtitle
+subtitle:
+  x: 150
+  y: 150
+  width: 575
+  height: 60
+  align: left 
+  valign: middle
+  font_size: 25
+# This one is completely new
+description: 
+  extends: subtitle
+  y: += 350

samples/layouts.rb

@@ -32,3 +32,10 @@ Squib::Deck.new(layout: 'custom-layout.yml') do
 
   save_png prefix: 'layout_'
 end
+
+Squib::Deck.new(layout:['custom-layout.yml', 'custom-layout2.yml']) do
+  text str: 'The Title', layout: :title             # from custom-layout.yml
+  text str: 'The Subtitle', layout: :subtitle       # redefined in custom-layout2.yml
+  text str: 'The Description', layout: :description # from custom-layout2.yml
+  save_png prefix: 'layout2_'
+end