Fix #140: show actual send timestamp also in message details

Signed-off-by: Daniele Ricci <daniele.athome@gmail.com>
Fix #1: retain fragment instance on configuration change (??)

This is probably an Android support library bug (or misinterpretation).

Signed-off-by: Daniele Ricci <daniele.athome@gmail.com>
Merge branch 'master' into xmpp_position (#51)

Signed-off-by: Andrea Cappelli <a.cappelli87@gmail.com>