Update Ctrl, Alt, Shift in real Update function
Update Ctrl, Alt, Shift in real Update function

Fixes #77

Turns out, if you get sf::Event::Released for Ctrl, Alt, etc.
event.key.control/shift/alt won't contain current state of the keyboard,
only previous one. So it's better to rely on real time input + now we
can handle left/right ctrl/alt/shift being pressed.

eliasdaler/imgui-sfml,EliasD/imgui-sfml,eliasdaler/imgui-sfml