Skip nested Feed when calling getNextUnreadFeed()

This function is only called when using "Mark all as read".
So every time, this function gets called right now, all nested
categories get marked as read as well, so we don't want to jump to them.
Instead we want to the next category with same or higher tier.
Merge pull request #379 from Joschasa/getNextUnreadFeed_skip_nested

Skip nested Cats/Feeds when calling getNextUnreadFeed()
af_comics: add extra fabulous comics
properly show cached images in syndicated feeds
rebase translations
Fix for testing filters getting stuck sometimes.

Sometimes when testing a filter the database becomes unresponsive, stuck
in a long query.

Solution: properly join ttrss_entries and ttrss_user_entries instead of
working with their carthesian product.
Merge pull request #381 from bram85/master

Fix for testing filters getting stuck sometimes.
Added curl CURLOPT_NOBODY option in geturl function to ensure the HEAD method is used when resolving permanent/temporary URL moves.
Added webkit-specific overflow scrolling for iOS devices to allow for inertial scrolling.
Merge pull request #382 from dzaikos/ios-inertial-scrolling

Enable inertial scrolling for iOS devices.
Updated cache_images() to use _MIN_CACHE_IMAGE_SIZE constant when checking file size. New constant is defined upon including rssfuncs.php if not already defined.
Merge pull request #385 from dzaikos/cache-image-size-2

Cache image size (take 2)
scroll to end to show next feed or category
only if cmd_auto_catchup and on_catchup_show_next_feed set
Merge pull request #386 from wolfgangasdf/master

After scrolling over all articles, show next feed or category automatically
mail plugin: only mail unique articles
mailto plugin: only mail unique articles
mail plugin: cleanup disabled completion, add configurable destination email list
mail plugin: destination dropdown css fix
Merge pull request #388 from dzaikos/fix-curl-head-request-method

Fixed geturl() function to ensure HEAD request method is used.
Update schema for size support of enclosures