Ensure that the decoder is init once only.

This fixes the crash while playing MPEG2 files with sequence display extension.
always process Startup.xml if it exists
add startupwindow infolabel
[Confluence] activate the selected startup window instead of home
allow <width>auto</width> for label controls, and ensure dirty-regions works with them. Part of #13887
Handle keystrokes in the web interface remote (up, down, left, right, play/pause, ...)
tag animations as ready to go once processed once, not while rendered once. fixes #13912
Speed up ffmpeg format probing if we'll trust codec fps.
Handle letters and digits keystrokes in the web interface remote
LinuxRendererGL: trigger reset of scaling when entering/leaving fullscreen video
VideoRenderer: add gui setting for threshold when hq scaling is desired
[python] Notify python code about double clicks
GUIScrollBarControl: fix onright/ondown navigation when master control doesn't have enough items to fill at least 1 page
GUIBaseContainer: remove unneeded call from CGUIBaseContainer::Render() - we are calling it in CGUIBaseContainer::Process() earlier
GUI containers: adjust page control offset when scrolling down to match behaviour when scrolling up
[Fix] work with non-ascii filter word which can not be seperated by space.
Merge pull request #2536 from ulion/non_ascii_filter_word_fix

[Fix] work with non-ascii filter word which can not be seperated by space
Merge pull request #2550 from pieh/scrollbugs

fix couple of scrolling / scrollbar bugs
Preserve playcount on file update

Attempt to preserve the playcount of a file when its updated (i.e. better quality file).
Episodes are matched on showID, season and episode.
Movies are matched on imdbID and year.
Merge pull request #2457 from nate1280/preserve_playcount

Preserve playcount on file update