Fix solution reconstruction

The developer has fully "grokked" the solution reconstruction phase, after identifying solutions from Gaussian elimination. The settings might be finicky, but the method looks like it should be sound (and mostly canonical), end-to-end.

Full Changelog: v5.1.7...v5.2.1

sha1sum results:
ffc65204998de930e720246b355d9d8a0a48fc94 FindAFactor-5.2.1-cp310-cp310-manylinux_2_35_x86_64.whl
3abafcb5ef0851e2577591446adf49e1f30c7a14 FindAFactor-5.2.1-cp312-cp312-manylinux_2_39_x86_64.whl
736cb256c692a9a7df490d2463b59da45bbd3e1d FindAFactor-5.2.1-cp312-cp312-win_amd64.whl
805e25e29f57507e4123b845af2dfab2ce50b917 FindAFactor-5.2.1-cp313-cp313-macosx_13_0_x86_64.whl
5ca4c7ff684ec4aef0b8ba354ffc90dfd71796ac FindAFactor-5.2.1-cp313-cp313-macosx_14_0_arm64.whl
84ec58eff5fdab32206989300f517bc56eab27f3 FindAFactor-5.2.1-cp313-cp313-macosx_15_0_arm64.whl
915d93cfa53a8da2c976916840601c7569998493 FindAFactor-5.2.1-cp38-cp38-manylinux_2_31_x86_64.whl
8c733777ef083a2f8a8f18269cbabc8cafc3309c findafactor-5.2.1.tar.gz