restore order of clauses in TPTP output; there's a rather subtle invariant w.r.t. "extract_lemmas"

optimize relevance filter by doing a Table.fold directly rather than destroying the datastructure each time; saves 2 sec per Sledgehammer invocation on my laptop!

output total time taken by Sledgehammer if "verbose" is set

Sledgehammer: the empty set of fact () should mean nothing, not unchanged

reorganize Sledgehammer's relevance filter slightly

tell the user that Sledgehammer kills its siblings

updated keywords;

replaced old Sign.add_tyabbrs(_i) by Sign.add_type_abbrev (without mixfix); misc tuning and simplification;

keep localized 'types' as regular non-old-style version -- 'type_abbrev' as 'type' just causes too many problems, e.g. clash with "type" in translations or "type:" argument syntax;

separate commands 'hide_class', 'hide_type', 'hide_const', 'hide_fact';

replaced generic 'hide' command by more conventional 'hide_class', 'hide_type', 'hide_const', 'hide_fact' -- frees some popular keywords;

allow syntax types within abbreviations;

modernized old-style type abbreviations;

modernized type abbreviations;

local type abbreviations;

merged

added original constant names to Sledgehammer internal terms + output short names if "debug" is set (for increased readability)

store nonmangled names along with mangled type names in Sledgehammer for debugging purposes

give more sensible names to "fol_type" constructors, as requested by a FIXME comment

make Sledgehammer's output more debugging friendly

made SML/NJ happy;

proper masking of dummy name_space;

salvaged some ML functors from decay, which is the natural consequence of lack of formal checking;

proper checking of ML functors (in Poly/ML 5.2 or later); eliminated pathetic comments;