Remove the following coercions because they make interval arithmetic much less trustworthy.

• RealField --> RealIntervalField
• float --> ComplexIntervalField
• SR --> ComplexIntervalField

For example, one could easily do the following by accident.

    sage: iv = 1 + 2^(-55) + 0. + RIF(1)
    sage: iv.lower(), iv.upper()
    (2.00000000000000, 2.00000000000000)

See also this topic on sage-devel

Already removed in other tickets:

• ComplexField --> ComplexIntervalField

CC: @videlec @mezzarobba @dkrenn @cheuberg @bhutz @JohnCremona @pjbruin

Component: coercion

Keywords: RIF RR interval coercion

Author: Marc Mezzarobba

Branch/Commit: 3c7644f

Reviewer: Vincent Delecroix

Issue created by migration from https://trac.sagemath.org/ticket/15114