Featured image links now stashed in a 7 day transient.
Reset transients on edit of post. Currently resets any time post is touched. Should only reset when featured image is changed.
Transient creation separated out into its own function. Transient is flushed and then rebuilt any time a post is saved. Fallback for non-existent transients in responsive image call.
Version number update
More precise handling of arrays.
Add link to WordPress Theme Directory, Picturefill license, and changelog.