ng2-dnd doesn't emit event when moving between sortable containers

[NimrodAvni]

• I'm submitting a ... [ ] bug report [x ] feature request [ ] question about the decisions made in the repository

• Do you want to request a feature or report a bug?

i would like an event that is triggered after items are moved between different dnd-sortable-container

• What is the current behavior?

The trigger OnDragSuccess and OnDropSuccess trigger only when items are reorderd in the same dnd-sortable-container, but not when they are moved between different dnd-sortable-container

• What is the expected behavior? have an new event that indicates if an dnd-sortable has moved to a new dnd-sortable-container

• What is the motivation / use case for changing the behavior? having a trigger when items are moved between containers is very useful when working with draggable objects

• Please tell us about your environment: angular: ^6.0.2 ng2-dnd: ^5.0.2 browser: all

• Other information (e.g. detailed explanation, stacktraces, related issues, suggestions how to fix, links for us to have context, eg. stackoverflow, gitter, etc)

[Chealer]

Can ticket #262 or this one be discarded?