Added window resizing solution using pageup and pagedown keys. Still glitchy though. Also, got back the instructions screen.
As of now, the spacebar is the button that will allow the bird to jump. We can make the mouse do the same, but as of now the spacebar is implementing this functionality perfectly.
Some physics issues regarding the bird and his flying animation needs to be worked out.

Signed-off-by: shrimpboyho <shrimpboyhoftw@gmail.com>