Merge branch 'master' into library-use-case

# Conflicts:
#	Cargo.lock
#	Cargo.toml
#	src/bin/scryer-prolog.rs
#	src/loader.pl
#	src/machine/mock_wam.rs
#	src/machine/mod.rs
#	src/machine/system_calls.rs

src/machine/parsed_results.rs

@@ -1,6 +1,6 @@
 use crate::atom_table::*;
 use ordered_float::OrderedFloat;
-use rug::*;
+use dashu::*;
 use std::collections::BTreeMap;
 use regex::Regex;
 use std::collections::HashMap;