Update predicates with improvements from Tim Dysinger

[oubiwann]

@dysinger created some nice implementations of various functions and macros in his lfesl project (so far only his thrushing macros have been copied over). In particular, I think I've seen a couple improvements there over what I've done for one or two predicates. That should be reviewed more carefully and then updated with his code.

See https://github.com/dysinger/lfesl/tree/master/include

See the older version of this issue for more context:

• Update predicates with improvements from Tim Dysinger lfex/lutil#14