Number_types: Add Filtered_rational

[afabri]

Summary of Changes

Add a class that combines Interval_nt and Exact_rational

Release Management

• Affected package(s):
• Issue(s) solved (if any): fix #0000, fix #0000,...
• Feature/Small Feature (if any):
• Link to compiled documentation (obligatory for small feature) wrong link name to be changed
• License and copyright ownership:

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Reason for draft: so far, there is no gain in performance.