Hashing algebraic numbers takes far too long

[rbeezer]

Hashing algebraic numbers can take a very long time. I've traced this to line 2421 of sage/rings/qqbar.py which can be re-created by the following code.

sage: A=matrix(QQ, 4, 4, [1, 2, -2, 2, 1, 0, -1, -1, 0, -1, 1, 1, -1, 2, 1/2, 0])
sage: e = A.eigenvalues()[3]
sage: K = (A-e).kernel()
sage: P = K.basis_matrix()
sage: x = P.list()[3]

sage: from sage.rings.qqbar import ANExtensionElement, AlgebraicGenerator, ANRoot, AAPoly
sage: QQbar_I_nf = QuadraticField(-1, 'I', embedding=CC.gen())
sage: QQbar_I_generator = AlgebraicGenerator(QQbar_I_nf, ANRoot(AAPoly.gen()**2 + 1, CIF(0, 1)))
sage: QQbar_hash_offset = AlgebraicNumber(ANExtensionElement(QQbar_I_generator, ~ZZ(123456789) + QQbar_I_nf.gen()/ZZ(987654321)))

sage: time h = hash((x + QQbar_hash_offset).interval_exact(CIF))

Time: CPU 58.31 s, Wall: 58.48 s