Fix bug that caused metadb database errors.

A missing WHERE clause caused sometimes all items to be updated
and, incidently, moved around to different folders

This was a regression since 4.5.110

Fixes #2010
ps3: Fix typo resulting in incorrect 'Unable to set RCVTIMO' warnings
ps3: Use 256 MB of virtual memory for Showtime's heap

This should eliminate various out-of-memory conditions that can
be seen during playback of high bitrate movies while using the
seek-by-time feature at the same time

Fixes #1878
Close thumbnail generator if no request has arrived for 5 seconds.

Reduces memory pressure a bit