Ensure effects are cleared for null local times
Avoid stashing for simplicity and size
Add test cases
Merge pull request #15 from alancutter/effectClearing

Ensure effects are cleared for null local times
Started implementing the normalize() method.
Sort keyframes by offsets. Other small changes.
Finished normalize() method. Now going to remove nested methods.
Create property specific keyframes
Finished making interplations.
Cleaned up comments
Sort and apply interpolations
Review comments
More review comments. Rearranged the steps in normalize to do
1. Clone/sanitize individual keyframes. Exception on NaN offsets.
2. Check for loosely sorted & unspecified offsets.
3. Remove keyframes with out-of-range offsets.
4. Sort keyframes. Exception if unsorted with unspecified offsets.
5. Space unspecified offsets.
Cast property values to strings
Check for null fraction
Clear properties if fraction is null