Merge pull request #103 from yanobs/master

Avoid updating feed based on user pref DEFAULT_UPDATE_INTERVAL if it is set to -1 (no update)
daemon2: wait longer between spawns (refs #647)
Revert "Avoid updating feed based on user pref DEFAULT_UPDATE_INTERVAL if it is set to -1 (no update)"

This reverts commit bca1cfbb9580d3ed295f7d93bbf4dce00eae8456.
daemon2: make update tasks to wait before starting updates to improve
last_update_started handling (refs #647)
headline menu: add ability to toggle unread/published/starred
cdm: make box-shadow a bit bigger; fix missing shadow on expandable active item
add hotkey toggle_cdm_expanded (f c)
support If-Modified-Since
if-modified-since: also take last_updated into account
update_rss_feed: bailout if cache is considered valid, but older than last_updated
daemon: show feeds/minute stats
daemon: sort by random
tweak daemon2 to run feedbrowser/etc tasks after update randomly, not instead of update
api: add author to getHeadlines