Function screen_draw_pixel 

pub unsafe extern "C" fn screen_draw_pixel(x: i16, y: i16) -> u32

Draw a single pixel on the screen using the current pen color

This function uses the following values of errno when an error state is reached: EACCESS - Another resource is currently trying to access the screen mutex.

\param x, y The (x,y) coordinates of the pixel

\return 1 if there were no errors, or PROS_ERR if an error occured taking or returning the screen mutex.