Integral library and the scaleless rule

The library (P15_integral_library.json) provides $A_0$, $B_0$ and the tensor reduction in $\hat{g}$. It is certified exactly in $d$ against Feynman parameters, and numerically at $d=2.6,3.3,3.7$.

The scaleless rule is stated, not assumed:

Its UV/IR reading is as follows. For $\omega =0$ the zero is the cancellation $1/{ϵ}_{\mathrm{UV}}-1/{ϵ}_{\mathrm{IR}}$. For $\omega \ne 0$ it discards a pure power divergence, and neither the UV part nor the IR part has a pole at $d=4$. Applying S0 to an integral that carries a scale is an error, and Missing is never replaced by zero by convention.