Added JSX namespace support; made reference comments wrappers for JSX elements.
Improvements to reference comments parsing.
Return undefined instead of null.
Merge branch 'patch-1' of github.com:RReverser/TypeScript
Added completion support inside JSX opening elements.
Moved reference comment processing to statement parsing.

* Reference comments can be placed anywhere in file and are parsed as
regular statements for easier processing.
* XJSExpressionContainer became descendant of ParenExpression
(expression is now node of `Missing` type instead of `undefined`).
Treat unfinished `<Ident` construct as JSX element for better completions.