Added HtmlRadioButton.
Refactored HtmlCheckBox.Checked logic into extension methods for reuse in HtmlRadioButton.
Updated DefaultHtmlElementFinder to filter out duplicate HtmlRadioButton instances.
Added performance fix for DefaultHtmlElementFinder for when wildcard elements are found in the search.
Refactored IHtmlElementFinder to remove redundant type parameter in BuildElementQuery.
Renamed HtmlTextElement to HtmlInput to be consistent with other elements.
Added virtual to several signatures.