Reorganize file structure per #18, added `main` tags as per #25
The start of a major SASS refactor, plus minor changes:

- Renames `external` to `components`.
- Changes responsive nav menu from a JQuery one to the slimmer approach at http://responsive-nav.com.
- Adds header icon support.
- Header layout adjusted as per suggestions in #16
- Images now resized using CSS3 `calc`, so we can pad `main` and still have images stretch to the side of the screen.
- Deletes theme options, as we will not be using custom colours anymore
- Changes next posts link to paginated navigation
- Simplifies default post format

The SASS is being rewritten as per #17: now we have only two files, `reset.scss` and `style.scss`, generating the main layout. The colour scheme will be defined in a third file.
Minor tweaks. Rename `/components/` to the more descriptive `/features/`. Improvements to HTML semantics.
Possibly controversial change removing support for comments.
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`
Colours! And minor tweaks.
- Moves all stylesheets to /css
- Adds default colour scheme for #28
- Cleans up preamble
- Changes breakpoint from `480px` (iPhone 4 height) to `586px` (iPhone 5 height) for #26
- Adds subsection numbers, inspired by http://css-tricks.com/numbering-in-style/
- Fancy footnotes too, assuming you're running my altered version of Civil Footnotes
- Remembered to style block quotes and site footer
Removes all unsupported default widgets (as per #29), including the Recent Comments widget which unnecessarily injects CSS into `wp_head`. Relatedly, I've rearranged the wp_head cleanup code as well.
A few small fixes:
- Better documentation as per #31
- footnotes.scss spun off as per #30
- New placeholder icon as per #33
- File type styles as per #34
- Monospace type for `code` tag
- Fix `figcaption` margins on small screens
- Add basic css file for external use (e.g. Marked.app preview)
- Civil Footnotes added as a basic theme feature
Getting closer to 2.0 release:
- Changes documentation style for main template files.
- Adds search bar to 404 page, per #35.
- Renames `css/style.css` to `css/main.css` for clarity.
- Adds root level `style.css` for WordPress requirements. Currently uses a superfluous `@import`, which will be replaced by an inline copy of the compressed and compiled `css/main.css` once SASS 4.0 is released.
- Conditionally includes Advanced Custom Fields, just in case child themes need to add more fields.
- Adds new favicon.
- Removes dynamic footer. It was cluttering up the bottom of the page.
- Adds `category.php` and `category-list.php` to begin work on #21 and #22.
Git Ignore
Code style improvements

Major code style improvements, including the following:
- consistent spaces instead of tabs
- removes ?> from EOF
- generally subscribes to PEAR coding styles
- puts documentation into a consistent format
- adds documentation to all Copernicus-original files
- removes some dead code
- consolidates all non-colour styles into one file

In addition, removes the embedded Civil Footnotes plugin and switches footnote style support to WP Markdown on Save Improved as suggested in #37.
Separate style and colour

Each page calls `colour.css` directly rather than including its rules in the main stylesheet. This change makes it easier to create child themes at the expense of one http request.
Reorganize styles folders

Rename `css` to the more accurate `styles` and merge it with `fonts` for good measure
Better support for child theme colour modifications

Wraps the call to the colour stylesheet in a conditional, so child themes can easily define their own colour schemes.
Minor fixes

- Stylesheets now compressed
- Header image now overridden by child themes
Update license to GPLv3
Update README, theme description
Category lists

Archive-type pages now display a list of posts, each with a thumbnail and excerpt, as per the discussion in #38. If the page is a category, it lists all subcategories at the top.
Major polishing

- Refactor and document stylesheets, `functions.php`, other files as per #31
- Tweak 404 and search failure pages
- Move `parts/content-templates/*` to `parts/*`
- Add empty alt tags to images missing them
Bug fixes

Move the main tag in `single.php` to the respective `parts` file (in order to add the appropriate class

Fix the main tag's class in `index.php`

Change category separator in `meta.php`

Remove unused colours