Added new sidebar format. Ajax calls now make of proper types of requests.

Removed 'simple_sidebar' preference, replaced with 'sidebar_style'.

Added 'fancy' sidebar style, which hides some controls behind menus.

Added '?' keyboard command to toggle an ugly legend of keyboard commands.
Added 'r' keyboard command to refresh the sidebar.

Added fof_db_mark_tag_read() to remove unread tag from all items with some other tag.

Ajax calls which change server state now all use POST requests.  Also now use hash objects as request parameters, so that encoding is automatic.
Further fancy sidebar features, now with in-situ updates.

Created new feed-action.php for handling updates of feeds in place from sidebar.

Replaced hard-coded image assets with map, defaults set in fof-asset.php, and overridable in fof-asset-custom.php.

Added image/tag-icon.svg ( sourced from http://commons.wikimedia.org/wiki/File:Black_book_icon.svg ) as a default tag icon.  Added image/spinner.gif and image/warn.gif from unknown sources.

Moved feed table row generation from sidebar.php into fof_render_feed_row() in fof-main.php, to be accessible via ajax.
Updated prototype.js to version 1.7.1, from 1.6.0.
Fixed sidebar mark-feed-as-read action.

Add the important little bits which perform that task.
Fixed mark-all-as-read in default style, fixed keyboard navigation.

Fixed incorrect variable in mark-all-as-read link generation of 'default' style in fof_render_feed_row().

Fixed keyboard navigation to use nextElementSibling instead of nextSibling, resolving the issue I introduced by putting line-breaks between item rows in item list html.
Reconciliation of some commits.

A fumbled local rebase required some finagling.  All's well.