show Tweet->created_at instead of wallclock in irssi window

[mmitch]

"capture" the irssi timestamp to show the creation date of a tweet instead of the wallclock time of the twitter poll. Timestamp format can be changed via twirssi_timestamp_format variable. This allows - if it is wanted - a visual distinction from the normal irssi timestamps.

Based on an initial commit by Gedge, but with a different timestamp display method.

[mmitch]

should the "original tweet time" be included in the logfile? I can't decide

[gedge]

implemented in latest beta