:sparkles: fix private methods to move in a local scope

  - SCSequenceableCollection#flatten
  - SCSequenceableCollection#flat
  - SCSequenceableCollection$flatIf
  - SCArrayedCollection::throwIfImmutable
  - SCDictionary::incrementSize
fix SCObject#_doesNotUnderstand -> SCObject#__attr__
:sparkles: fix namespace accessing
:fire: remove code unused
:sparkles: fix how to append a property

  - use `$.addProperty` instead of directly assignment
:sparkles: fix to require needed
:sparkles: move definition of SCScript interface

  - The Interface of SCScript should be appended a method in `sc/sc.js`.

fix tests

:muscle: fix SCScript interface
:sparkles: fix variables not to reference from outside
:lipstick: fix how to use 'strlib'
:sparkles: fix tests which use a stub of console
build v0.0.62