fix options splitting and merging to not lose some kwargs

if we passed certain options after passing global override options (ie. passing an image spacing option before passing a repetition option), the first global override option was lost

lib/spritely/options.rb

@@ -23,8 +23,10 @@ def [](key)
     def options
       @options ||= stripped_hash.except(*GLOBAL_OPTIONS).inject({}) do |h, (key, value)|
         split_key = key.to_s.split('_')
-        option = global_options.merge(split_key.pop.to_sym => value)
-        h.deep_merge!(split_key.join('-') => option)
+        option = {split_key.pop.to_sym => value}
+        image = split_key.join('-')
+        h[image] ||= global_options.dup
+        h.deep_merge!(image => option)
       end
     end
 

spec/spritely/options_spec.rb

@@ -2,18 +2,18 @@
 
 describe Spritely::Options do
   let(:hash) { {
+    'some_new_image_spacing' => Sass::Script::Number.new(789),
     'some_new_image_x' => Sass::Script::Number.new(123),
     'some_new_image_y' => Sass::Script::Number.new(456),
-    'some_new_image_spacing' => Sass::Script::Number.new(789),
     'another_image_repeat' => Sass::Script::Bool.new(true),
     'yet_another_image_repeat' => Sass::Script::Bool.new(false),
-    'spacing' => Sass::Script::Number.new(901)
+    'spacing' => Sass::Script::Number.new(901),
   } }
 
   subject(:options) { Spritely::Options.new(hash) }
 
   its(:inspect) { should eq("#<Spritely::Options global_options=#{{spacing: 901}} options=#{{'some-new-image' => {spacing: 789, x: 123, y: 456}, 'another-image' => {spacing: 901, repeat: true}, 'yet-another-image' => {spacing: 901, repeat: false}}}>") }
-  its(:cache_key) { should eq({some_new_image_x: 123, some_new_image_y: 456, some_new_image_spacing: 789, another_image_repeat: true, yet_another_image_repeat: false, spacing: 901}.to_s) }
+  its(:cache_key) { should eq({some_new_image_spacing: 789, some_new_image_x: 123, some_new_image_y: 456, another_image_repeat: true, yet_another_image_repeat: false, spacing: 901}.to_s) }
 
   its(['some-new-image']) { should eq({spacing: 789, x: 123, y: 456}) }
   its(['another-image']) { should eq({spacing: 901, repeat: true}) }