Remove dependency on mirror.  Remove getInterpolatorByType, interpolate List, Map, Object for performance issue.
Remove references to convenient utility functions for user to get interpolators and easing functions internally so tree shaking can happen for project that doesn't use these functionality and have better performance.
Merge pull request #32 from midoringo8823/bug_fix

Help tree-shaking out some code by cleaning up internal usages of utility methods.