This fixes the following issue:
1. bridge sets unique ids for the items (ids get hashed)
2. items go to the cache
3. on next run items get loaded from cache
4. these items have different ids because they were hashed again
5. they show up twice in feed reader
'uid' represents the unique id for a feed item. This item is null by
default and can be set to any string value. The provided string value
is always hashed to sha1 to make it the same length in all cases.
References #977, #1005
Add transformation from legacy items to FeedItems, before transforming
items to the desired format. This allows using legacy bridges alongside
bridges that return FeedItems.
As discussed in #940, instead of throwing exceptions on invalid
parameters, add messages to the debug log instead
Add support for strings to setTimestamp(). If the provided timestamp
is a string, automatically try to parse it using strtotime().
This allows bridges to simply use `$item['timestamp'] = $timestamp;`
instead of `$item['timestamp'] = strtotime($timestamp);`
Support simple_html_dom_node as input paramter for setURI
Support simple_html_dom_node as input parameter for setContent
