Add Pharo-like handy Object >> #putOn: and Stream >> #<< for streaming
Small SequenceableCollection refactoring:

- Only sequenceable collections can be streamed
- Moved some methods to SequenceableCollection
Fixes issue 428:

Mutable literals should be aliased too in cascades
Fixed HashedCollection >> withIndexDo:
Collection tests refactorings and improvements
Stream improvements and tests
Merge branch 'master' into helios