Updated tests & results: Language declarations

These tests examine whether language information is available for text processing when declared in various different ways.

The format of the tests was improved, and the 6th test page was dropped (dealing with language attributes on block elements) since it replicates tests elsewhere.

The results were rewritten to reflect behaviour of the latest major browsers.

Update: An error was fixed in test page 3 and three new test pages were added, to examine the effect of multiple language values in the meta element and precedence of language attribute and meta element. The tests were re-run and the results page updated. [search key: test-lang-decl]