Allow overriding keydown.enter action when inline editing

[myleshk]

When input editor.type is "input" or "textarea", ENTER key will trigger saving, and such behavior is hard-coded in src/ng2-smart-table/components/cell/cell-editors/input-editor.component.ts:

(keydown.enter)="onEdited.emit($event)"

This variable $event is passed all the way up, not exposed or processed but discarded at src/ng2-smart-table/components/cell/cell.component.ts, so we cannot change this behavior:

onEdited(event: any) {
    if (this.isNew) {
      this.grid.create(this.grid.getNewRow(), this.createConfirm);
    } else {
      this.grid.save(this.row, this.editConfirm);
    }
}

This is a problem in the following situations:

• When typing non-alphabetic languages like Chinese, ENTER key can be part of the typing process (e.g. charactor selection). If this happens, inputing process is interupted and intermediate content saved unwantedly.

• In textarea mode, it is likely that you want to input multiline text. Then when you try to break a line by pressing ENTER key, it will save instead, also unwantedly.