Merge branch 'amin/logrel-nat-to-int' into 'master'

theories/logrel/F_mu_ref_conc/binary/context_refinement.v

theories/logrel/F_mu_ref_conc/binary/examples/counter.v

theories/logrel/F_mu_ref_conc/binary/examples/fact.v

theories/logrel/F_mu_ref_conc/binary/fundamental.v

theories/logrel/F_mu_ref_conc/binary/logrel.v

theories/logrel/F_mu_ref_conc/binary/rules.v

theories/logrel/F_mu_ref_conc/lang.v

theories/logrel/F_mu_ref_conc/typing.v

theories/logrel/F_mu_ref_conc/unary/examples/symbol_nat.v

theories/logrel/F_mu_ref_conc/unary/fundamental.v

theories/logrel/F_mu_ref_conc/unary/logrel.v

theories/logrel/F_mu_ref_conc/wp_rules.v