Linked list API rework:

1. *Value methods renamed
2. replace added
3. dup validation removed
Add Iteration for LinkedList
Iterate: cleanup and refactoring
Enable Iteration for Array
Rework Iteration to pass extra information to iterating function

At the moment extra information is:
- absent for LinkedList
- index for Array

It is planned to send key for Map
Rename LinkedList to List
Fix Travis CI and README
Increase version to 0.2.5
Merge branch 'feature/iteration' into develop