add FAA to atomic_heap

See merge request !844

proofmode: do not treat pure assertions as persistent

See merge request !799

Make sure that `Make` instances are consistent and "constant time".

See merge request !838

add limit_preserving_impl'

See merge request !839

Make BI operational classes consistent: always use `PROP:Type` instead of `bi`.

See merge request !840

Generalize Propers for lists

See merge request !837

get rid of make_laterable in atomic triples

See merge request !835

Move `Make` classes/instances to their own file, and improve documentation

See merge request !836

Rename `_plus` into `_add`.

Closes #472

See merge request !821