Custom implementation of extractSelectedHtmlFromRange.
Tests: Improved tests for extractSelectedHtmlFromRange.
Return artificial extracted HTML in editable.extractSelectedHtmlFromRange.
Tests: Check if editable.extractSelectedHtmlFromRange returns extracted HTML.
Enabled possibility to return string from editable.extractSelectedHtml. Update selection after extraction.
Fixed: editable.getSelectedHtmlFromRange retrieves wrong HTML for multi-row tables.
Tests: Added test for multi-row table.