Links: refactor & improve URL cleanup

Links: refactor & improve URL cleanup

Relates to #141
Relates to #133

Modifications
 - move URL cleanup to `application/Url.php`
 - rework the cleanup function
   - fragments: `#stuff`
   - GET parameters: `?var1=val1&var2=val2`
 - add documentation (APIs the params belong to)
 - add test coverage

Reference
 - http://php.net/parse_url
 - http://php.net/manual/en/language.oop5.magic.php#language.oop5.magic.tostring

Signed-off-by: VirtualTam <virtualtam@flibidi.net>