Add lemmas `big_sepM2_inv_{l,r}` and rename `big_sepM2_lookup_{1,2}` into `big_sepM2_lookup_{l,r}`.

See merge request !692

Add lemmas `big_sepM2_delete_{l,r}` and rename `big_sepM2_lookup_{1,2}` into `big_sepM2_lookup_{l,r}`.

Document `iInduction ... using` tactic.

See merge request iris/iris!682

Explicit visibility for Instances

See merge request !684

Fix typo

See merge request !687

explicitly declare visibility of Scope actions

See merge request iris/iris!679

rename big_sepL_sepL2 → big_sepL2_sepL (and similar for sepM)

See merge request !676

add atomic exchange operation

See merge request iris/iris!675

Better %I scope handling

See merge request !674

Append-only list RA

Closes #391

See merge request !661