BUG: 'click' can set a year to zero if the option 'widgetParent' is specified

Steps to reproduce:
1. Set the option `widgetParent` to point to an element inside `<SPAN></SPAN>`.
2. Open a picker and try to select some text inside a calendar: move mouse while holding the button
3. Inside `click` handler `e.target` is equal to TBODY or TR.
4. `target` variable is equal to `$(e.target).closest('span, td, th')`, so it points to SPAN element which is the parent of specified `widgetParent` (see step 1)
5. `year = parseInt(target.text(), 10) || 0;` - year is equal to 0.