Bug 1961 partial: move urlParse() into class URL

Bug 1961 partial: move urlParse() into class URL

* rename local variables in urlParse() to avoid symbol
  clashes with class URL members and methods.

* move HttpRequest method assignment out to the single caller
  which actually needed it. Others all passed in the method
  which was already set on the HttpRequest object passed.

* removed now needless HttpRequest parameter of urlParse()

* rename urlParse as a class URL method

* make URL::parseFinish() private

* remove unnecessary CONNECT_PORT define

* add RFC documentation for 'CONNECT' URI handling

* fixed two XXX in URL-rewrite handling doing unnecessary
  HttpRequest object creation and destruction cycles on
  invalid URL-rewrite helper output.