Footers!
- Adds a small site footer, customizable via widgets.
- Adds a footer for post metadata — post date, last updated, categories, tags, credits, and photo credits — shown in `single` view.
- Adds Advanced Custom Fields to implement "credits" and "photo credits" fields for each post.
- Adds icomoon icons for metadata.
- Removes genericons, which have not been used in the last couple commits.
- Minor tweaks to `style.css`, including permuting CSS properties.
- Slightly better documentation in `functions.php`