succesful build & debug & new demo

- created a game called "2-Player Tetris" to demonstrate usage of gui
framework
- introduced text_button class with text centering functionality
- created event.cpp for functions like is_numpad_key
- every include window.h is preceded by UNICODE macro
- changed glwindow creating policy, now can use config with hardcoded
variable names
- introduced password_mode flag for drafter
- get_member_children as solution for static gui members