Added adjustable camera-height and updated camera-movement

Ahoi, I made some changes to the game, as I had some suggestions concerning the camera behavior.
I changed the camera-movement to feel a little more "natural" and maybe less vomit-triggering.
Also I added the possibilty to move the cam up and down via the mouse-scroll-wheel.
Along with some gameplay fixes, I hope you enjoy these changes. If not please let me know.
Best regards, Jens