Reduce a polynomial times a high half-odd power of a quadratic with numbers for coefficients

[Rafael-SOWNet]

Part of #718.

Welz's 1/((3 - 2 x + x^2)^(11/2) (1 + x + 2 x^2)^5) and its ^(21/2), ^10 twin were declined, though 1/((3 - 2 x + x^2)^(9/2) (1 + x + 2 x^2)^4) is answered. SolveARationalFunctionBesideTheRootOfAQuadratic splits them into pieces. A piece over the first quadratic is a polynomial times its half-odd power. SolveAPolynomialTimesAnOddHalfPowerOfAQuadratic reduces it to R Q^(k + 1/2) + K/sqrt(Q) by one linear solve, and three things stopped that:

1. A cap. The numerator could be of degree 8 at most, and the power at most 9/2. Welz 103 leaves a degree-9 piece over the eleventh half power, and Welz 104 a degree-19 one. With numbers for every coefficient the system stays small, and the caps are now degree 24 and power 25/2. With symbols they are as they were.
2. Named coefficients. A coefficient written as an expression, such as -2 written as a product, was named for the solve as though it were a symbol. The system then ran as an elimination over expressions, and its values came to 552,490 nodes against a bound of 250,000, so it was refused. A coefficient free of symbols that evaluates to a rational is now that rational.
3. The solve. With every entry a rational number, the system is now solved by Gauss-Jordan elimination in exact rationals, with each value reduced to lowest terms as it goes. PeterO's rationals are not reduced on their own, and unreduced, the solve for Welz 103 took 563 s.

Checks

• Exact checks at 50 and 300 digits on the two Welz integrals, the 11/2-beside-a-square case and two direct pieces: 40/40.
• AHighHalfPowerOfAQuadraticBesideAPowerOfAnotherIntegralTest: 3 cases.

Corpus, measured against master 90c9d3e (this branch then merged 1e79b0e):

	master	this branch
pocket: the algebraic pocket and every row of 4.1.7, 4.2.7, 6.1.7, 6.2.7 (8,745 statable)	8,697	8,697
family 0, whole (1,814)	1,787	1,789
rows moved		+2: Welz 103, 104

Both solve on this branch re-run alone (0.07 s and 0.2 s) and neither on master. No losses and no slower rows. Gate passed; suite 15,467 passed, 0 failed.

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