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* move PROP-envs definitions to environments.v so that we can control them without pulling in coq_tactics
* use reduction-controlled `pm_default` for proofmode accessors

If the BI is not affine, this should not happen, as it may lead to
information loss.

This commit fixes issue #190.

move test suite out of theories/ so it does not get installed; also check output of test suite so that we can test printing

Thanks to Robbert for fixing gen_heap

The WP construction now takes an invariant on states as a parameter
(part of the irisG class) and no longer builds in the authoritative
ownership of the entire state. When instantiating WP with a concrete
language on can choose its state invariant. For example, for heap_lang
we directly use `auth (gmap loc (frac * dec_agree val))`, and avoid
the indirection through invariants entirely.

As a result, we no longer have to carry `heap_ctx` around.