#5827: Improve torrent files tree updating performance

Do not unnecessarily emit dataChanged signals for items which didn't change.
Cache file item indices to speedup lookup.
As a bonus, this also fixes wrong file progress display in rare cases.


git-svn-id: file:///data/workdir/Transmission-svn/trunk@14345 1bcf1a7e-6170-4b50-b784-84ec52b2dec6
#5800: Add Ukrainian translation to Qt client (patch by olexn)


git-svn-id: file:///data/workdir/Transmission-svn/trunk@14346 1bcf1a7e-6170-4b50-b784-84ec52b2dec6