refactor |createURI|

* cache a spec without the hash part
* add a base domain and testing utility
improve test of excluding links that would not be 'prev/next' navigation

* check duplicates in cache first of all
* add base domain check to avoid jumping to the outside by a 'prev/next' link
adjust the settings for finding sibling navigation
rewrite array item checker
minor fix

* sort constants in order of the definition of type
* fix typo
* update comments
update preset of navigation