Added safety to st_animation_frame() and created st_animation_frame_current_nochange() (same as st_animation_frame_current but doesn't itterate the currentframe) and st_animation_frame_set() for setting an animation's current frame.
Added safety to st_animation_frame() and created st_animation_frame_current_nochange() (same as st_animation_frame_current but doesn't itterate the currentframe) and st_animation_frame_set() for setting an animation's current frame.

BtheDestroyer/SpriteTools,BtheDestroyer/SpriteTools