fix #955 Multiselect - problem in labels with spaces

When labels for multiselect items have trailing spaces, the value in the field is not interpreted correctly. Selected options are not recognized as such, so they get deselected.

While writing a test case, another small issue in the widget width computation has been spotted and fixed.
fix #954 Improvement of the focus template API test

An existing test (test.aria.templates.focusAfterRefresh.FocusTemplateTestCase) has been improved in order to actually test that the focus is given back to the widget that had it before a refresh.

Close #959.
fix #970 aria.utils.Date.format can now handle falsy values and empty objects

It now returns `null` in those cases instead of failing with a `TypeError`.

Close #971.
fix #969 SynEvent used pageYOffset and pageXOffset on all version of IE

These properties are not supported on IE <= 8
(http://www.quirksmode.org/dom/w3c_cssom.html#windowview),
and returned undefined.

Now a fallback on scrollTop and scrollLeft has been done if
these properties doesn't exist.

Close #898, close #664, close #635, close #663