update StringAlter
Add core methods

+ core.bubbledVariableDeclaration
+ core.createScopeVariableDeclaration
+ core.findParentForScopes
+ core.getNodeVariableNames
Arrow function bugfixing
Add spread support

Update local esprima
spread tests
Destructuring refactoring

Using last variable as temporary variable
Cache Array.prototype.slice to variable
Fix bug with SequenceExpression (tests/de6-destructuring.js::33:63)
arrow function test
Spread bugfixing

Force to clone array if array is not a last expression in spread