Refactor to remove obsolete design and improve code consistency.

Refactor to remove obsolete design and improve code consistency.

1. Remove isValid()/validate() in Filter; EffectAction would push
filters into the stack when being notified by notifyChanged().
2. Make RedEyeAction consistent with DoodleAction by ignoring
out-of-bounds operations.
3. Improve consistency by encapsulate effect-tool creation/removal in
one class (EffectToolFactory).
4. Minimize variable visibility in EffectAction subclasses.
5. Fix unfinished doodle lost when exiting Doodle effect by multi-touch.

Change-Id: I8d3b127c5fe8777eb45b7c5ae680f6a30a99635a