Cross-section linearization for incident charged-particles using reconr

[dlopezaldama]

Cross sections in MF3 for charged-particle evaluations are usually linearly interpolable, but some use alternative interpolation schemes. When using reconr to linearise them, consider that MF3/MT2 data may include negative values near threshold energies.

Avoid calculating redundant cross sections, as this can lead to double-counting in ACEFC.

For photoatomic or photonuclear data, a more precise treatment of threshold energies is recommended.