fixed phpdoc for Request::url function params

Removed

* @param   array    $params    URI parameters
fixed phpdoc for test_url function
add the failing test
add a condition to test if the url is external
default to original ini setting if Cookie::$domain not set

We should not let PHP override the default setting if Cookie::$domain is not set. Otherwise it will send cookies with the host name of the server which generated the cookie.
Adjusted ternary operator to comply with coding standards
Make it more readable, as suggested by @WinterSilence
Merge pull request #443 from enov/bug/4241/request-url-external

Fixes #4241 Request::url() should return URI if it's external
commented comments to a multi line comment block

as suggested by @Zeelot
Merge pull request #447 from enov/bugfix/3604/Session_Native-Cookie-domain

Fixes #3604: default to original ini setting if Cookie::$domain not set