fix log-window bug

1. add the log-window a HSCROLL window sytle
2. fix bug under window platform that the insert positon shoulde focus on the last
Merge branch 'master' of https://github.com/XimingCheng/HEVCAnalyzer
change thumbnail load method

1. add a class member that denote file length (in BYTE)
2. firstly load a fixed image then change to real thumbnail
Merge branch 'master' of https://github.com/XimingCheng/HEVCAnalyzer

Conflicts:
	HEVCAnalyzer/MainFrame.cpp
	HEVCAnalyzer/PicViewCtrl.cpp
	HEVCAnalyzer/PicViewCtrl.h
Merge branch 'master' of https://github.com/XimingCheng/HEVCAnalyzer

Conflicts:
	HEVCAnalyzer/PicViewCtrl.cpp