Minor fixes and case sensitivity

Mostly just case sensitivity (Uint8 vs uint8) changes so that this works after bigbreak

Also: 
1) I changed the get/set mouse position procs so that they imported from libcsfml-window.
2) The -, -=, and +/+= operators for TTime needed some tweaking.

I'm not really sure how the newClock procedure finds the Clock_Create() procedure, so that might need to be changed back to import sfClock_create from libcsfml-system? I didn't change it since I thought you're probably doing something clever.  :)