Fixes invalid character in license header
Cleanup: moving feed list node removal dialog from feed_list_view.[ch] to feed_list_node.[ch]
Add credit also in plugin metadata
Preparing a popup notification plugin. Refactored subscription_update to trigger a signal 'new-items' in FeedList. Added properties to LifereaShell to get instances of FeedList, ItemList, ItemView and BrowserTabs to be used by plugins to register to signals.