Fetch and compare each query parameter.

Problem/Motivation

We now use a full link comparison to match the canonical link with SEO.
This was implemented as an initial trial version. We need to rework it.

Proposed resolution

How we can do this:
* add a new hidden multivalue text field
* when saving a reference, we need to also save each non-empty parameter with a value in a new field
* when comparing links, also compare non-empty parameters in the functions: getSeoUrlByCanonicalUrl() and getCanonicalUrlBySeoUrl()