Fix issue #1738: [datatable-sort] Sort order inconsistent when comparing on equal value

This pull request address issue #1738, where datatable sorting on equal values does not always return the same result. The issue is especially important in paginated tables, where inconsistent sorting could leave out rows when moving from page to page, or what could be seen as missing data. Check the issue for jsbin examples.

As a tiebreaker in the event that values are equal sorting is based on the insertion order, determined by parsing the model's clientId.

Included in this PR are unit tests, inline comments, and a small spelling correction in the docs.