Merge "[Windows version] WindowImpl cleanup, fixes and improvements." into devel...

diff --cc dali/internal/system/windows/timer-impl-win.cpp
Simple merge

diff --cc dali/internal/window-system/windows/platform-implement-win.cpp
Simple merge

diff --cc dali/internal/window-system/windows/platform-implement-win.h
Simple merge

diff --cc dali/internal/window-system/windows/window-base-win.cpp
Simple merge

diff --cc dali/internal/window-system/windows/window-base-win.h
Simple merge