#32 - Refactored Const_Windows.h to use class notation

* Renamed Const_Windows.h to Const_WinUser.h
* Added new consts
Closes #32 - WindowHandler - Make use of new Const_WinUser.ahk
Merge branch 'feature/#32_winuser_h' into develop
[*] Windowhandler - Refactored property-notation to be consistently using []