Version 4.6.1 - Sledgehammer Eval

Few fixes and extensions on top of 4.6.1 motivated by a Sledgehammer evaluation on https://martin.desharnais.me/17-provers/2021-11-18/problem-examples.tar.lz
On top of master (106b95b), we also include two experimental schedules sh_hydra_fol and sh_hydra_tf0.