solve_ndisj: solve more goals involving chains of differences

See merge request !300

rename map_union_subseteq_l_alt → map_union_subseteq_l' (and likewise for _r)

See merge request !301

Swap `curry` and `uncurry` to be consistent with Haskell and friends.

Closes #76

See merge request !297

This also applies to `(un)curry{3,4}`, `gmap_(un)curry`, and `h(un)curry`.

This fixes issue #76.

The code includes a horrible hack that should removed once support for Coq versions prior
to 8.13 is dropped.

alternative implementation of mk_evar that keeps naive_solver working

Closes #115

See merge request !299

handle more goals in solve_ndisj

See merge request !294

Do not call `done` recursively when solving `is_Some`.

See merge request !296

add mk_evar tactic (to replace Coq's strange evar tactic) and use it

See merge request !289

Make `done` work on `is_Some`.

See merge request !293

Fix priority of `Permutation_app'`.

Closes #114

See merge request !291

add lookup_union_l

See merge request !292

This is a workaround for https://github.com/coq/coq/issues/14571

This fixes #114.