[rbp] Fix for hang after seeking introduced by ASS fix

#2206 introduced a regression when seeking in some types of SD files where the video stutters and/or stalls.
This is caused by using the wrong clock in FlipPage
Fix for AlarmClock(): Prevent freeze-up when time <=0 and loop = true
Combine 2 CGUIWindowManager::SendThreadMessage methods with default param.
fixed: Stream details for current file were not stored when item was not in the db yet
fixed: Media flags didn't load for non-db items
changed: Check for streamdetails in the db before storing them
changed: Check whether streamdetails exist in the db before storing them
changed: Remove incorrect comment
fixed: The VideoThumbLoader didn't fetch streamdetails for items that didn't have a file id set in their infotag