misc: & => &&
EventFilter: internal. new API. remove old filter if a new is registered
examples: simple player, videowall. move remove gui dir
version 1.1.7

Changelog
- scale image without qt support!
- buggy ipp support.
- thread safe capture
- Fix first frame not correctly decoded!
- new API
- tests and examples: clockcontrol, videowall
remove dependence of EventFilter because it's a internal class
realloc memory for image converter if format changed
Fix Qt5 building error

QT += widgets
QCoreApplication::argc() does not exist in Qt5
update clock using another clock
misc: building, FFmpeg spell etc
video wall: sync to external clock
Merge branch 'master' into delay