honor "metisFT" in Mirabelle

make "full_types" take precedence over "type_sys"

crank up Metis's timeout for SMT solvers, since users love Metis

generate a "using [[smt_solver = ...]]" command if a proof is found by another SMT solver than the current one, to ensure it's also used for reconstruction

make sure first-order occurrences of "False" and "True" are handled correctly -- this broke when adding proper support for higher-order occurrences

consider "finite" overloaded in "precise_overloaded_args" mode

added timeout max for remote server invocation

fix translation of higher-order equality ("fequal") if "precise_overloaded_args" is "true"

fix Vampire parsing problem

improve partially tagged encoding by adding a helper fact that coalesces consecutive "ti" tags

example tuning

remove at most one double negation -- any other double negations are part of some higher-order reasoning and should be left alone, cf. "HO_Reas.thy"

weaken the "expect" flag so that it doesn't trigger errors if a prover is not installed

added example to exercise higher-order reasoning with Sledgehammer and Metis