Revert the revert :)

- BrowserVersion: remove deprecated FIREFOX_3_6, FIREFOX_10, CHROME_16, INTERNET_EXPLORER_6 and INTERNET_EXPLORER_7.
- HtmlElement: remove deprecated getElementById() and .hasHtmlElementWithId(), and remove UrlUtils.encodeUrl().


git-svn-id: svn://svn.code.sf.net/p/htmlunit/code/trunk@8652 5f5364db-9458-4db8-a492-e30667be6df6