Add _opam to .gitignore

See merge request iris/iris!900

Add order operations for locations in HeapLang.

See merge request iris/iris!854

add 'wp_apply (...) as'

Closes #452

See merge request iris/iris!884

move style guide into repository

See merge request iris/iris!899

Turn `internal_eq_entails` into a bi-implication

See merge request iris/iris!898

Make `unseal` tactics type-directed

See merge request iris/iris!778

Fix typo in appendix

See merge request iris/iris!895

Also, refactor the file so that all type class + canonical structure instances
are at the same place, instead of spread through the file.

Move definitions and lemmas about heap_lang locations to module `Loc`

See merge request iris/iris!890

Improve iCombine to allow a 'gives' clause for validity properties

Closes #460

See merge request iris/iris!872

Rename `f_contractive_core` into `dist_later_intro`.

See merge request iris/iris!896

Change definition of dist_later for compatability with Transfinite Iris

See merge request iris/iris!886