Fixed shadow bug

Shadows were still visible when a ShadowedObject visibility was set to
false
added screenPercentX and Y, some cleanup

-remove todo text
- added screenPercentX and screenPercentY to get percentage of screen
for positions
- renamed CENTER_X and CENTER_Y as POSITIONS might be moved to a friend
variable for use by the user
AnimationSets, "kinds" of animations, onTick animations

- removed todo text
- addition of "repeat" config option for yoyo and loop
- added initial setup for animation "kinds" - transition, loop, yoyo or
continuos
- in progress work of onTick for animations
- added initial work for AnimationSets with a few added
- added base.frame to PropertyAnimation
updated todo and issues
Pushing example objects

These are still a WIP and not really worthwhile except for examples.