Add support for retina images
Add retina JS
Add code to create directory structure
Add miscellaneous entries to replacement array
Fix some bugs
Re-add aliases
Replace retina.js with srcset
Update to use srcset in img tags to avoid potential server issues with retina.js (IPB is quite image heavy)
Update documentation
Fix template padding issue
Merge pull request #1 from mdave/master

Add retina support, subdirectories and tidy code