[do not merge] dirty selection model for angular and react

[krausest]

This is currently not intended to be actually merged.
This implements the dirty model (selected is part of the row model) for discussion in #772

[whittet]

If you check if each row === selected, like the main branch does, then changing the value of selected will cause all rows to need to be checked by change detection. When using @for and track by item.id, then changing the id of the two rows that you are changing here should be a 500 times faster solution. For more detail read on. Best wishes and very impressive benchmark. Although this one number appears wrong for angular.

Each iteration of the loop is checking length, but it can be set once.
Only one item in the list has clazz = 'danger', so looping all items is not the optimal solution.
Simply store the index of the selected item in a class property; use this value to find one row to set to ''.
this.selectedRowIndex = this.data.indexOf(item);